On and Off Lean Condition

[RedTalon95]

I was driving back to Philadelphia Sunday night when all of a sudden my car bogged down while I was doing about 60~ in 5th. My A/F gauge was pegged lean. I hadn't done anything to provoke this and was just cruising when it started. I couldn't keep the car up to speed because it was bogging so bad when I touched the gas pedal and didn't want to stress it while it was running so lean.

I pulled over to the shoulder and turned the car off. I checked all sensors, couplers, vacuum lines, etc for something that was out of place or disconnected but no luck. I started the car back up, ran fine for about 45 seconds back down the highway. After that, same thing happened. I dropped the car in neutral and just let it coast until about 20 and put it back in gear to pull off at the next exit. The car ran fine again for the next 30 seconds or so, then went back to doing the same thing - lean condition and bogging when trying to accelerate. I managed to limp the car home by riding out neutral as much as I could, thankfully it was late at night.

This one really confuses me. I don't understand why putting the car in neutral temporarily fixes the lean condition. Also, and this could just be me, but it seemed as though the longer I had it in neutral the longer the car drove well before going back to running lean. Anyone have any suggestions? I'm going to check it out this weekend and just wanted to get some ideas because this one has me stumped.

 

[TALONTRAX]

Sounds like fuel starvation, possibly a clogged fuel filter or a failing fuel pump or pump relay. I`ve seen a fuel pump relay failure cause this problem, the contacts in the relay overheat, & cause a voltage drop to the pump & it intermittently shuts down or runs on low voltage causing a lack of fuel pressure/volume, hence the lean readout on your guage . . .

 

[awdclipse]

I had the same problem. It would run fine, then out of no where it would start missing and had no power. Then when I put it in neutral and let the rpms drop it would be fine for about another minute then start up again. For me it ended up being a blown sensor ground in the Ecu, just something to check out...

 

[BklynsDsmer]

yea was about to say the samething . its your ecu, i had to send mines out . Check your injjector pulse .

 

[VETTE_50_TH]

I vote for a clogged fuel filter first, than a ecu. Not because its not, but its cheaper to replace a fuel filter than an ecu. I would also, just for shits and giggles, do a compression test too and a boost leak test. One more thing, do you have any logging software? Check you logs and see if something could have been acting up there.

BTW, go the the tristate forum, and go to my thread about the second annual meet, i would like to see you come. Its down towards Philly and the more the merrier.

James

 

[RedTalon95]

I will replace the fuel filter this weekend. I don't think it's the fuel pump since it's pretty new, but then again I've seen new things go bad as well. I will consider that if the filter and ecu aren't the problem.

How would I go about testing the ecu? Any other way besides swapping it out with a good one? I have a logger that's running Palm'N'Stein.

James, I'll check it out .

 

[BklynsDsmer]

yea thats the only way to find out if its your ecu swapping it out thats how i found out about mines, sent it out to jeff he told me samething it was a ground in the ecu that fried. So get a swap real quick and fnd out