Need some help figuring this one out. My car intermittantly moves in and out of limp mode while driving, If I push in the clutch and rev it it will go away sometimes. It seems to happen while decelerating or when I chop the throttle most often. Car has new Magnecore wires, filters (paper) rotors and caps, coils and fairly new Mafs and DKs. Plugs are fresh (couple thousand miles) and look new.:help:help:help

Is this the turbo you just got not too long ago?
Do you get any engine check lights during those issues?


Need some help figuring this one out. My car intermittantly moves in and out of limp mode while driving, If I push in the clutch and rev it it will go away sometimes. It seems to happen while decelerating or when I chop the throttle most often. Car has new Magnecore wires, filters (paper) rotors and caps, coils and fairly new Mafs and DKs. Plugs are fresh (couple thousand miles) and look new.:help:help:help

Pinned, What kind of plugs did you put in? There have been some issue's with the kinds of plugs that are put in the M70. Just some food for thought. Later Carter

No engine check lights and the plugs are stock, Runs like a raped ape when its normal. The limp mode started suddenly and seems to be getting more frquent......

Eight Ball is right about the plugs....did you use the stock Bosch's?

Yes I used stock bosch plugs. Does anyone know of a source that lists all the different things that can cause limp mode. I would like to systematically check for known issues and work my way around the car.:help

What is it doing? Is it runnning on half a engine when limping? Could you check the exhaust to see if only one side is getting hot.

sounds like possibly MAF, dirty DK Motor(s), O2 Sensor,or even the wires themselves. Have had experience (not so good) with wires that are NOT OEM - I am also not alone here on that one.
Check the distributor cap and rotor, especially the center contact. Another thought might be to look at the fuel pump for that side (I assume it is always the same side). Fuel filters can also cause problems if they are clogged pretty bad.
Then there is always the usual "other" stuff that would need to be eliminated like Fuel Pressure Regulators, vacuum lines to the FPR, air leaks at the rubber boots BEHIND the MAF's.
You will have to go by process of elimination, and remember to change or check only one item at a time.

No engine check lights and the plugs are stock, Runs like a raped ape when its normal. The limp mode started suddenly and seems to be getting more frquent......
#6 or #12 plug wire/sensor. Is it always same side that goes dead? If so, which one? Do you have one of your old wires to ts with? Double check MAF connectors. Does it run for a few seconds and then limp? Or does it start immediately in limp?

The car runs on half its cylinders (or so it feels) down on power struggles slightly to get up to speed, rough idle etc. I checked the exhaust when it was in limp mode and it was even temps on both sides. Also of interest my vacuum/boost gauges were just about even during the event(s). If I roll on the throttle the gauges seem to re-act evenly so it appears the DK's are working. (they are new within 5k miles and i have had them apart to check them and they are cherry (clean and still have lube on gears etc. motors/windings look day 1 new as well). While hooked up to car they open evenly although not all the way (I understand they wont unless motor is over 3 thousand rpms). Distributor cap and rotors are new (250 mi). Wires are Magnecore 8mm (100mi), MAFS are clean and look very new (P.O. replaced them). Correct me if I am wrong TX but doesnt the FPR only come into play during idle? I was under the assumption when they get a high signal they relieve or drop pressure at idle and as soon as they get a drop in vacuum they stop regulating and allow full pressure to the rail? My issues are very different in that they are intermittant they really have no pattern except they seem to happen most often when I chop the throttle or at low throttle positions. Are there any known wiring looms or areas of concern that can cause this.....I hate to keep repeating these checks over and over and not get anywhere...........

SSC, It starts normally and runs for awhile then just starts going in and out of limp mode with no rhym or reason.......doesnt seem like its one side or the other (see above symptoms)

correct on the FPR. I would look at the MAGNACORE, as well as the signal wire for #6 and #12. Another thought might be the CPS is starting to fail. These wires get very brittle since they are right up against the block of the engine - it only takes a little bit to get an intermittant signal (been there, done that too). How many miles do you have on the car? and have the CPS been replaced at some point?

Car is at 160k and I dont believe the crank sensors have ever been replaced. What kind of symptoms did you have when your CPS went out?

intermittant power (more like surges, as if someone connected and disconnected a bank of cylinders). I had ohmed out the wires and they were still within specs. Only after the car wouldn't crank anymore and I replaced them, did I find that the sheilded wire portion was broken (right under the fastening clamp wher you can't visually see it). My CPS went out at 161,350 miles - could well be your problem. Not a bad idea to replace anyway. You need to loosen the power steering pump mounting bolts to get to the bottoms one, but if you get the pair from Autohausaz.com, they are the 'new" style and will go in much better than the originals.

Good luck

Rodger that thats kind of what the car used to do, if I stood on it it acted like it was down on power then if I lift and restand on the throttle (pin it) it comes back. This deal seems worse now only because it happens down low (RPMS). (I think) Is there an easy way to check the CPS?

OK ordered the CPS x 2.........

I still wouldn't rule out the #6 or 12 plug wire/sensor. Do you have a spare to test with?

No I had to use them with the new wires.......

Ok changed out CPS sensors (along with belt pullies while i was there) and I still get an intermittant limp mode.......pullin my hair. I checked out the CPS after removing them and one of them didnt ohm out (had an open terminal). Thought I found the culprit, oh well next..........plug wire sensors I suppose. What do you guys think Ohm check em first or change em out?

Both fuel pumps working? Check the opposite side fuel pump where the engine comes and go's. Same for the ignition coil. The route your going, It's gonna run like new when the problem is located.

Yeah it should...ill give it a shot. (coils are new but ill still check em out) Thanks .....

Ok I Ohm checked out the pulse sensors/cylinder id and have 1 ohm between pins 1 and 2 and nothing between pins 2 and 3 on either side......im really confused now. should be less than 1 ohm for 1 & 2 and more than 10 M ohms for pins 2 & 3......any ideas? neither side specs out. If the system was working correctly shouldnt it shut down fuel to those banks (in this case both) and not run? Any ideas? Not sure I trust the Ohm test.......

Did you happen to accidently cross the CPS sensors?

Its not possible the way they are routed and the length of the cables they will only plug into the correct spots.....if you mean am i checking the CPS plugs no they are only a day old and waaay too clean to mistake.....

Not starting at all now? When the ignition is turned on right before the starter turns, Do the fuel pumps come on?

No car starts fine its an intermittant limp mode. My current issue is the intermittant limp mode. Checked out coils and they too dont match the repair manuals Ohm check numbers....im beginning to think the manual is suspect. Both sides are exactly the same

Yes fuel pumps run when you turn the key on. Its weird because my intermittant limp mode comes and goes whenever it wants but when it does if I shift gears and let out the clutch its normal for a min. Also if I shut her down and re-start it goes away..........????? Im baffled.....I beginning to lean more towards the fuel side of things but knowing the lack of or incorrect signal shuts fuel down its tough to figure out where to go.

When you're driving and it goes into limp mode have you noticed black smoke come out of the exhaust?

No extra smoke.....

So no limp in idle or park ..only when you're moving! Any particular speed? Any particular weather conditions like when it rains! and do all your gauge lights work when you first turn the key on.!

It will continue to limp at an idle it just comes and goes at it pleases. No particular speed(s) no particular weather....all gauges work Eml etc etc........

Starting to sound like a short, I would wiggle some connections to see if it would limp, Including some of the wires on the postive side of the passenger side battery.

Let me clarify one question..At idle while the car is moving or at idle when its parked?

Intermittant problems are my favorite. Its like trying to pick a needle out of a hay stack. There's times when you go through your tool box and you run across a hammer and you think to yourself hmm..I bet that will fix it. lol but that won't work obviously. Here's what I would try..Its kinda old school but effective..I call it the "tap" technique. Get a medium sized screw driver, grab it by the end(flat head end or phillips end etc) and start taping the connections. Actually the best way to find a faulty MAF sensor without using a diagnostic tool is while the car runs tapping on it, the car visually starts running rough. Now I don't mean beat the living S*&#@ out of it. Just a mild tap. I see your mafs are new but tap em anyway. Tap the connections anything you see connected just tap it and observe the engine while its running. If everything visible checks out rig a tool like a long screwdriver or a pry bar or a long socket extension that wont interffere with anything while the motor is running on connections that you cant get to. While you have your jig ready start the car and then try to move the connection of course with care and observe if the limp mode appears. Also while the car is running wiggle the wire going to each spark plug. If you have a bad wire you will see the difference and maybe if your lucky it might even bite ya. Its not rocket science but I have a feeling youll find it.
GL
http://images1.zoomonga.com/photos1/ed94bb11-8a9b-4d3e-8c1d-a8542ad92c1d_small.jpeg

Ill give it a shot............

Both fuel pumps working? Check the opposite side fuel pump where the engine comes and go's. Same for the ignition coil. The route your going, It's gonna run like new when the problem is located.

Fuel pumps.

I had this problem as well my friend. It ending up being a small plastic inlet for one of two fuel pumps became old and weak and simply broke off causing surging because fuel was not getting pulled properly into the pump, I changed them both then it ran fine again. Remember both of my fuel pumps were running fine... so you don't know until you pull them out from underneath the rear seat and check fo visual damage. This plastic gets old and gasoline doesn't help it's age one bit.

Alrighty then first chance I get ill eyeball the pumps. I know the pevious owner replaced at least one pump so maybe the other is having issues........thanks for the suggestion

Ok I am ready to hang myself with a fanbelt...I checked fuel pumps and now I am in full time limp mode. I got 100psi at the pump(s) @ fuel tank outlet and also got 100psi at the back of the motor..... The car is in permanent limp mode so I exchanged DME wiring harnesses and the same side is still in limp (pass). Swapped MAFS and same thing they are both good. Guess Ill replace the whole car next. Anyone????

swap the DME connects back to original, MAF's are fine where they are. Pull plug wire on pass side closest firewall. Pull it at the dist also. That wire should meter 6k ohms +-10%. It's a pita but you can swap wire sets temporarily and check that way. If the wire or sensor to the DME is bad, you have the symptoms (almost starts normal and then immediately goes into LHM). It could be as simple as the wire is not fully on that plug, ck that first. Good troubleshooting so far, you're almost there!
So far we know the DME,MAF,CPS,fuel,coils are good. If all that cks ok, pull that spark plug and visually verify it's firing. If any doubt, swap it with another one.

Rodger that. I have pulled the connection(S) to the pulse sensor and when i pulled the one on the side not in limp mode it would die as above (run for a second then die) but the other didnt make a difference. Im thinking because its already in limp mode its not making a diff. I will try the checks you said and will update when done....thank you

it could also be a tranny related issue guys, i don't think i've seen anyone throw that out there yet. i'll check bmw tsb's tomorrow when i goback to school to see if i can find anything out for you. usually when u get limp mode it's to protect the engine and keep u from damaging it more than what has already been done.
also when ur checking connections have another person rev the engine,basically check them at idle and at different rpms.

it could also be a tranny related issue guys, i don't think i've seen anyone throw that out there yet. i'll check bmw tsb's tomorrow when i goback to school to see if i can find anything out for you. usually when u get limp mode it's to protect the engine and keep u from damaging it more than what has already been done.
also when ur checking connections have another person rev the engine,basically check them at idle and at different rpms.

Not V12's in 850's. Different animal.

Rodger that. I have pulled the connection(S) to the pulse sensor and when i pulled the one on the side not in limp mode it would die as above (run for a second then die) but the other didnt make a difference. Im thinking because its already in limp mode its not making a diff. I will try the checks you said and will update when done....thank you
Starting to sound like plug wire/sensor.

Alright im fit to be tied I am so friggin frustrated I cant even begin explain........I just changed the pulse sensors (new from Gault) and I am still in limp mode.............give me a fanbelt so I can hang myself please. So far I have checked fuel pumps (get 90-100 psi at intake) replaced crank position sensors, pulse generators, car has new coils and I have swapped sides to check, swapped MAF sides, swapped DME's, new plugs, new wires....you name it. It has gone from intermittant to permanent limp mode...........any ideas that dont require selling it? (although I am contemplating it). I did a stomp test and I get 1247 and a 2247 ignition secondary monitor.....................I have ohmed the wires and all are within specs..........

Only thing I didn't see on your list were the distributor caps and rotors.

My question is When did this all start? Did it start after you replaced the spark plugs and wires? If so might want to start back at the beginning. Try putting your old wires back on and see what happens. Might have a bad set of wires. Just a thought. Also what is the type of plug? I know you told us oem but which one? The old type or the new type? Give us the spark plug number please. I know it is like kicking a dead horse, just keep on smiling and try. Hope you get it solved soon. Take care. Regards Carter


Now where is that fanbelt?:rolleyes

Yeah I forgot to mention new distibuter cap and rotors (done). It has been happening since for awhile intermittantly but getting worse over time. Thats why I have been changing parts.

What brand wires did you use?

One of the guys from Texas got a couple of non-functioning aftermarket sets in a row IIRC.

Hang in there pinned...

yes, he sure did. They were both KINGSBOURNE wires and they S U C K E D !!!

yes, he sure did. They were both KINGSBOURNE wires and they S U C K E D !!!

I was blessed with a set of those fine examples. Stuck me for the afternoon at the first SE8 Gathering in Florida. Borrowed some wires and drove home. Beru is what you want.

I put magnecore wires in. They ohm out at 4k ohms up to 6k depending on their length (through the cap). Also Bosch F8LCR R1 and F8LCR R6, Autolite 5224 (copper). All with the same results........

So Pinned, When did this start happening? After or before you started replacing parts? Please reply. Lets go backwards in time and it might be easier to pin down (forgive the pun). Thanks as alway. Regards Carter.

Do you still have your old wires? Might want to give it a go.

This all started BEFORE I replaced parts. This is the whole reason I started replacing them.
When replacing the old wires I found some were broken some were repaired at some point and all needed to be replaced. I thought I had found the problem but no not to be. So I have continued to chase it. The car does not have spark at all on the limp side......I was thinking if it was fuel related that I would still have spark just no fuel.....not sure if the DME's can tell if there is no or low fuel. Does any one know what triggers limp (besides cps and pulse sensors) ? And if there are different modes of limp ie no fuel pump only, no spark only or both together and what it means? Again stomp test shows 1247 and 2247.


Jim

Pinned, Hate to say it but might be time to take it in. All the parts you replaced need to be replaced anyways. (At least it sounds that way). Know this is not what you want to hear but sometimes you just need to bit the bullet. Better solution then the hanging yourself from the fanbelt. Just trying to look on the upside. I wish you luck sir. Take care and please keep us informed. Regards Carter

Jim,
Can you list (preferably in order) the pieces you DID replace since trying to figure this out. I am sure we can narrow it down for you.

S.

Not sure what taking it in is gonna do.......except spend my cold hard earned cash. (I dont trust dealers or mechanics anymore). Someone has had to have had this happen to them.....I thank you just the same though and I appreciate your response(s).

Sure Steffan, First was air filters, then caps and rotors, Spark plug wires, Crank position sensors then spark plugs and finally pulse generator on affected side. I have another but didnt do it yet. I checked fuel pressure at the pumps and the firewall. I have swapped MAF's, Coils, and DME's. I pulled the DK's off and apart (they were new inside and out) I did some other maintenance stuff along the way (oil changes, idler pullies etc).

jim

Alright im fit to be tied I am so friggin frustrated I cant even begin explain........I just changed the pulse sensors (new from Gault) and I am still in limp mode.............give me a fanbelt so I can hang myself please. So far I have checked fuel pumps (get 90-100 psi at intake) replaced crank position sensors, pulse generators, car has new coils and I have swapped sides to check, swapped MAF sides, swapped DME's, new plugs, new wires....you name it. It has gone from intermittant to permanent limp mode...........any ideas that dont require selling it? (although I am contemplating it). I did a stomp test and I get 1247 and a 2247 ignition secondary monitor.....................I have ohmed the wires and all are within specs..........


Okay, another question: you say the car has new coils. Did you buy new coils, or were they recently replaced? The reason I ask is because on my 850 the 1247 & 2247 code (IGNITION SECONDARY MONITOR) were bad coils. Before anything drastic, exchange the plugs on the DME's and see if the problem changes sides.

Even though a coil "ohms out" correctly, they may be screwed up enough to not deliver the juice once under a load. There is really no good way to check the coil once it is "lit up" (under load) without electrocuting the crap out of you. Do you have a spare coil you could troubleshoot with?

I dont have a spare but I will buy a new one to check. Its funny because I swapped sides temporarily and it worked. I have receipts from the previous owner and they are only a couple of years old (5k miles). I wonder if the reason I am getting this code on both sides is because I swapped them.......I have swapped plugs on the DME's and it stayed on the same side.

Coil would make sense as it used to go away (not limp mode) when I shifted gears (changed load)

Steffen, how did your car act when the coil(s) went out? It seems I have power to the coil (both terminals) but it doesnt spark. when I swapped sides it worked on the passenger side. I did not however ground the coil when I checked it I just layed it on the passenger side while testing.

Back to hanging myself. I swapped coils again just to be sure before I went and bought another disappointment and they both work fine. They both worked on the passenger side of the car. They both dont work on the driver side, and have 13+ volts incomming on both sides.................F*&^%

okay, so it's not the coils... What happened when you switched the DME's?
Remember, only swap one component at a time to see if there is a change.

DME's are good (problem stayed on same side). I also rechecked fuel pressure and swapped DK motors and problem remains on same side.

Check the pulse sensor/sender on the #12 plug (the donut around the sprkplug wire). If you have a spare, try just that wire and sender. If you don't you could take the #6 wire and swap with the #12. If your problem hops to the other side - you have found the guilty party. It is worth a try before you go and buy wires...

...another thing to check is to see if you mixed up the plugs for the CPS and the pulse sender for #12 (been there, done that!)

Already replaced it with a new one (pulse sensor and plug wires) with no change. Is there a relay for each of the DME's? Or are there any other relays that could do this?

Jim, Have you checked your air flow meters ie connection to? Just a thought. This is starting to really bug me. Thought that a solution would have been found. I have been thinking and went over to RF and this is what I found. Please click on link. Hope this helps. Keeps us informed. Regards Carter

http://forums.roadfly.com/forums/bmw/bmw-8-series-e31/search.php?st=intermittant+limp+mode&dosearch=Go

Yeah its really buggin me too.....been a couple of months worth of diagnostics, parts changing and a whole lotta cussin!! I swapped MAFS but dont know how to check the connections at the wiring looms. I really am getting worked on this thing. It has to be something on the driver side wiring or ???? I have swapped sides on everything there is and it stays on the driver side. It now starts and stays in limp mode. I did some more checks and it does not get a signal at the injectors or the coil.........and thanks for the link I have been reading every related link from every forum there is in hopes of finding something..................................

What were you changing when it went from Intermittent to full time limp mode?

Had a J-spec here in LHM and after trying most of the stuff mentioned in this thread, with the engine running I pulled each fuel pump relay. First one killed the engine. Replaced, second one made no difference. Replaced 2nd relay and car ran on all 12. They are in the same E-box as the DME's, blue as I recall. Pull both and switch them. If problem switches sides - you have a flaky relay. Worth a shot.

Jim, I think it might have something to do with the wiring also. Does anyone know how to test a mass air flow while it is still in the car? Had a probem with the limp mode once. Just replaced the rubber boots between the DK's/mass air flow and the mass air flow/air filter box. I started up the car and it was in limp mode. After about an hour of looking around, gave the wiring connector that comes into the MAF's a twist. On one side I hadn't installed the connector all the way. Started car back up, problem gone. It might be the connector or the wiring. Just a thought. Check the fuel pump relays as Wuffer described also. Hope it gets fixed soon Can hear the cussin up here. Take care. Carter :rolleyes

Thanks guys will do.....................

Well Tom, I tried the relays and no change swapped them amd problem stayed on drivers side......it was worth a try. Terry there was no change from intermittant to full time that co-incided with a parts change it has been gradual and continued to increase in frequency until it didnt go away. Ok Carter, on to checking wiring at the MAF's...thanks guys for all the imput I really do appreciate it.....

Jim

Starting to sound like a faulty fuel pump!

Nah been there, tested good at pumps and at firewall...both sides.

FPR's test good too?

Not sure that they have the ability to move the car into limp mode...but I have not tested them. I think they only come into play at idle. I am open to suggestions though.......

HELLALUYAH...did I spell that right? LIMP MODE FIXED (er figured out)..I repeat LIMP MODE FIXED.......yeah hoo. Anyways I made some calls arount to other TT owners and no one had any of the above mentioned issues with their cars so I called Dinan and spoke to a fella named Sean Wheeler. He did some research and came up with some ideas. Turns out that the ignition retard/boost electronics bypass the stock firing signal at the coil. I bypassed their system (back to stock) and I have 12 humming cylinders again.... Ok I figured it out but now have to see why the box is not working and have to stay out of boost until its fixed (man thats gonna be hard). I want to thank all of you that contributed and gave me ideas to try, you guys are really appreciated by this 8 owner and if anything it got me and my car intimately aquainted. (and boxes of new parts)
Thanks again
Jim

Alright, Thanks god that is over. Got some good leg work out of that problem. Congrads Jim. Now keep that foot off the gas. Well at least until the problem is fixed. Good to hear it is done. Cheers. Carter

:redspot:buttrock:redspot:buttrock:redspot:buttroc k:redspot:buttrock:redspot:buttrock:redspot:buttro ck:redspot:buttrock:redspot

That's great news, Glad your back up and running, Thanks for posting the fix, That's always plenty helpful.

yes, he sure did. They were both KINGSBOURNE wires and they S U C K E D !!!

Only somewhat on topic, but wasn't it the Karlyns that were crap, not the Kingsborne? Shopping for wires and general consensus has been stay-away-from-Karlyns....

Only somewhat on topic, but wasn't it the Karlyns that were crap, not the Kingsborne? Shopping for wires and general consensus has been stay-away-from-Karlyns....


... and KINGSBOURNE. No 2 wires in those sets metered out the same. On the first set of mine the pulse sensors were dead. The ONLY way to go is BERU (OEM). There was a guy about a year and a half ago that had aa bunch of sets that he was selling for $139 a pair (yes, you read that right), he started selling the crap out of them and then raised his price to $189 a pair. I have been trying to get in touch with him , but have had no luck.

Thanks for the clarification...will go Beru...if you find those good deals would greatly appreciate any heads up!

Dont forget about magnecore wires- very nice pieces. You can get them 2 ways with or without pulse generators. You can re-use your old ones (they will leave #12 and #6 uncrimped at cap end) or you can buy new ones or they can buy them for you and send them complete. Pulse generators are about 80 bucks from Gault and wires were 160 shipped IIRC. (I bought the 8mm wires and they fit into origional loom holders, a little tight but they fit). They ohm @ 2-3kohms per foot of length and dont deteriorate like stock ones seem to.