After nearly two months CEL free, the familiar light came on during a hard acceleration onto the freeway.

There were two codes about a small leak being detected in the evaporative emissions or something like that -- and "O2 sensor adaptation limit reached bank one."

The fuel trims for both banks are negative 7.8 or so. (-7.8) (What can be causeing the car to be needing to subtract so much fuel?)

The AFR on one of the banks reads centered right about 14.7 or so at idle.

These large negative numbers have been there ever since the TS was installed.

The o2 sensors are 10,000 miles old, and I recently replaced the fuel pressure regulator.

If anybody could advise me on what to check this time around, I would really appreciate the help.

Thanks,

I know exactly how you feel brother.....what was the code, E3? CA?

The Autoenginuity version of the code is E3, also known as P36e3.

I'm trying to stay calm this time -- not do anything rash...

There must be some perfectly good reason this is happening......

Do you have a Walbro? And did you read fuel trims 50+ miles after you replaced the FPR? Refresh my memory.... do you have a fuel press gauge? I also seem to recall that a lot of the TS's have crappy S/C-to-head gaskets. Were you the one that replaced it fairly recently?

On a side note, I just got my new FPR in the mail today (I dragged my feet on this one, I know. :) ) so I will let you know if that was my problem or not as soon as I install it.

John,

How old is your fuel filter? What are your WOT AFRs?

Do you have a Walbro?

I think I do.

And did you read fuel trims 50+ miles after you replaced the FPR? Refresh my memory....

I don;t recall. That was back in October and the gaping hole that appeared in my intake gasket overshadowed everything else that was happening then.

Besides, I have an Autoenginuity code reader that doesn;t actually read LTFT and STFT like it promises.


do you have a fuel press gauge?

Yes, still in the plastic molded package it came in. I don;t know how to use it yet, and am puzzled with how to get readings at o vac o boost and 5 lbs boost, given that vac appears to not easily go to zero with the car sitting still. (is my vac guage whacked too? )


I also seem to recall that a lot of the TS's have crappy S/C-to-head gaskets. Were you the one that replaced it fairly recently?


Tell me about it. Does twice in the last 12 months count as recent? The VAC motorsports gasket appears to be holding.

On a side note, I just got my new FPR in the mail today (I dragged my feet on this one, I know. :) ) so I will let you know if that was my problem or not as soon as I install it.

Looks like you have more patience for automotive trouble than I do.

I will be interested to hear if you find your throttle response to be crisper.

Thomas,

Good to see your calm help again. Thanks.

How old is your fuel filter?

I don't even know. I think it was replaced at 80K...maybe 48,000 miles ago..... Um....Ok, I think I might have let that one slide.

OK, so it's probably been too long. Will that make the car have too much fuel?




What are your WOT AFRs?

I see them dropping right into the low 13 range when I floor it, until over 4K or so, and then they drop below 13 -- 12.6 or 12.8 or so? (It all happens so fast.)

This fuel trim at -7.8 or so has been constant through all I hve checked along the way.

I did notice the car idle a slight bit rough when I parked it tonight. I sprayed the hell out of everything with the MAF cleaner and found no leaks this time. After the car cooled again, it idled smooter again.

I'm sure you have heard.... Walbros have been said to kill stock FPRs. Not sure how much truth there is to this. Might be mostly circumstantial. Also, you may want to check your HFM or clean it. It will generally throw a MAF related code if it is bad, but you never know for sure.

I don;t recall. That was back in October and the gaping hole that appeared in my intake gasket overshadowed everything else that was happening then.

Besides, I have an Autoenginuity code reader that doesn;t actually read LTFT and STFT like it promises.

Yeah, I remember now. That kinda sucks. Maybe look into another scanner. It's a good investment.

Yes, still in the plastic molded package it came in. I don;t know how to use it yet, and am puzzled with how to get readings at o vac o boost and 5 lbs boost, given that vac appears to not easily go to zero with the car sitting still. (is my vac guage whacked too? )

The fuel press gauge is pretty simple to install... you should do that as soon as possible. Reading it will be a no brainer once you have it in.

Tell me about it. Does twice in the last 12 months count as recent? The VAC motorsports gasket appears to be holding.

Haha! yeah, that counts. At least that should not be an issue now.

Looks like you have more patience for automotive trouble than I do.

I will be interested to hear if you find your throttle response to be crisper.

I too am interested to se the results. I bought a supposedly good used one.... it was bad. So I bought a new one then went on vacation for a month.

I wouldn't call it patience so much as lack of funds. :( ....and lack of time. Almost every expensive part on my car needs to be rebuilt or replaced at once, it seems. I have been troubleshooting and replacing suspect parts. Gets real old, real fast. Y'know?

Get rid of OBD2, and I would bet all of your issues will magically disapear.

Your issues are not a new thing. When you can't stand it anymore, buy a TEC3 or convert to OBD1.

-Dave

I'm sure you have heard.... Walbros have been said to kill stock FPRs. Not sure how much truth there is to this. Might be mostly circumstantial.


I periodically got the code for adaptation limit over the 58,000+ miles that I've had the twin screw. However, it hasn't been a problem since I installed an Aeromotive fuel pressure regulator.

While not necessarily confirming the inadequacy of the stock fuel pressure regulator, it certainly does suggest that the stock unit may be overwhelmed by the Walbro pump and unable to divert enough fuel back to the tank in low load situations -- which would cause negative long term fuel values.

Neil

Wouldn't the code derive from too much fuel at a part throttle condition, do you think this is what causes the fuel issues with the Walbro? It would seem to me that the fuel pump would overwhelm the regulator more at WOT, my trims are excellent on my car with the stock regulator and a Walbro.

Wouldn't the code derive from too much fuel at a part throttle condition, do you think this is what causes the fuel issues with the Walbro? It would seem to me that the fuel pump would overwhelm the regulator more at WOT, my trims are excellent on my car with the stock regulator and a Walbro.

Jim -

I'm no expert at this stuff, but the fuel pressure regulator doesn't need to divert much fuel back to the tank at WOT. Problem is more likely to occur at idle and part throttle situations.

Neil

Good point, I wonder if the car was originally designed to be tuned with a Walbro that might explain the problem in the first case.

I periodically got the code for adaptation limit over the 58,000+ miles that I've had the twin screw. However, it hasn't been a problem since I installed an Aeromotive fuel pressure regulator.


Thanks Neil. Where did you get this, and does it fit in the stock location?

Were your fuel trims also at -7.8 before the switch to the new FPR?

Wouldn't the code derive from too much fuel at a part throttle condition, do you think this is what causes the fuel issues with the Walbro? It would seem to me that the fuel pump would overwhelm the regulator more at WOT, my trims are excellent on my car with the stock regulator and a Walbro.


Thanks Jim. Before I replaced the FPR the first time, last October, my fuel pressure was starting out a hair high, and was 5 PSI high at zero vac/zero boost. When 5 lbs boost was added, the pressure went up by 15 more PSI. So the pressure got further off spec the more throttle. You hypothesis about overwhelming at WOT is suppoorted by the data from my car before I replaced the FPR.

Now we've heard from two other TS people besides me that fuel pressure may be a problem.

Any ideas for what to do this time are most welcome.

So far suggestions:

New fuel filter
Go to OBDI -- (can't do that)
New FPR --

Good point, I wonder if the car was originally designed to be tuned with a Walbro that might explain the problem in the first case.


Jim C's tuning did take the Walbro into account, but I believe this is more of a hardware issue than a tuning issue.

Neil

I think Neil is right about tuning vs. hardware.

I have fuel pressure data now:

Idle --

50 lbs at 19 in. of vacuum.
60 lbs at 0 vac 0 boost
60 lbs at practically anything over 1 lb boost.

Should be:

40-45 @ idle
47-50 @ 0 vac 0 boost
+1 for every lb. boost (eg., 53-55 @ 5 lb boost.

I'm assuming the tune does not drive fuel pressure, so it must be hardware like Neil said.

Next steps I'm taking:

1. Lines plugged in right? Installer may have reversed them.
2. Reference vacuum working? (Reading vac and boost, right?)
3. Swap fuel filter

watch this space for more gripping news as it unfolds.

I have normal vacuum at the FPR.

Fuel pressure increases when vacuum decreases.

I replaced the fuel filter and the pressure at idle is the same.

There appear to be no restrictions on the fuel return line.

I'm at another dead end for now. (Still haven't forgotten the Aeromotive fuel pressure regulator idea. I wanted to check further into some other basics first.) Any ideas? As it stands now, I'm going to order the Aeromotive FPR Monday.

Thanks,