So my a/f gauge in my turbo 95 cobra says I'm running lean...only really on the highway or if I somewhat beat on it (even the slightest bit)...problem randomly started...also get a check engine everytime I start to go lean but it clears by the time I get off the highway so I don't really even have time to check it...I plan on getting a scanner in the next day or 2 but any ideas of what the issue is?

 

Need WAY more info to really be able to help you? Blowthrough or EFI? What kind of motor combo? etc.....

 

If he gets a check engine light its efi. What code is it throwing? How lean is it going? And what do you mean by only on the highway? Is it fine at the track?

 

Yes it's a 95 cobra 5.0 EFI motor...stock with a 70mm turbo. By the time I get somewhere to check the code it clears...and i noticed its not 100% on the highway but majority of the time it is. I'm starting to believe it's when I give it a certain amount of throttle? It's just so aggravating it doesn't even let me check the code because it clears before I get to it...I know I'm being vague on details but I'm just lost and trying to make some sort of progress?

 

What type of fuel pump ??

 

What engine management are you using for this engine? Does it have the ability to data log the problem?

 

need a way to monitor fuel psi. it's efi and your boosting O2 is calling for more fuel. fuel pump might be max on the hi-way

 

I have a 340 lph on3 fuel pump. Unfortunately I have no ability to data log. And I don't see how it could be the fuel pump, I've had the tune for about 2 months now and never had an issue, even when ripping on it. This is happening when I'm just cruising between 2k-3k..

 

Filter or kink in fuel line ??

 

Here's just a thought that crossed my mind...my catch can is vented to atmosphere. It was just laying under my hood but recently I shoved the hose into my wheel well so it would be a little more hidden...maybe that's causing it to not vent properly since it's pretty much an enclosed area?

 

do you still have a pvc hooked up? if so, you could be getting unmetered air through that vented catch can. run either just the catch can with no pvc hooked up (capped off) or just the pvc with no catch can. just a thought

 

So finally got to scan it...I got a MAF fault, only runs lean when I'm at a somewhat aggressive throttle. The MAF is new and only been in the car since August. Could it be a possibility it's just dirty or not really?

 

Not sure if it's the same type unit, but I used to maintain a fleet of Crown Vic and Grand Marquis, and we had to clean the Mafs every few months.

 

it can't hurt to take it off and clean it. Mke sure you solder all connection if you had to extend your maf wires

 

On the ones we were working with, they would start stalling, idling funny, fuel mileage would go down, etc. Feedback was from taxi drivers, so the info from them wasn't great, but we used brakleen, cotton swabs and shop air to clean them. We VERY seldom had any codes, but the MAF reading were usually off a bit, and straightened out after cleaning. If they were really bad, we would clear the memory for a relearn as well.

 

My 94 cobra had this issue. It was my o2 sensor where I had extended it. Would run fine but once I tried holding higjway speed chug chug cel come on. Let off and it cleared up. Check them for being fouled up with soot. Yes the maf could also be dirty. Cobra computers suck donkey dick fwiw

 

Did you have to replace your o2 sensor or is there a way to clean it? Maybe I'll give that a shot

 

Cleaned them with carb cleaner. Soaked them for a few minutes in a cup of it let them dry and reinstalled

 

So FINALLY put my wideband in and tossed that POS a/f "light show" gauge. Under boost I'm rich which my tuner set it as...it actuallys run decent most of the time but randomly it'll peg so lean it can't read it and I'll tap the throttle violently and it's as if I just woke it up and a/f goes back to normal...and cold start up it runs pretty lean upwards like 16-18 randomly...any input on this? Still think that would be an o2 turbofreek? Similar to your issue?

 

Mine ran lean at cold start idle. It helps heat the sensors up quicker and the engine. Light throttle it was between 12-14. When I lifted a touch off the peddle it spike lean. Which was normal. I'd almost say check your plugs for a possible headgasket issue. When mine started acting up it gsve up the ghost and windowed the motor. On the highway while cruising. So take it serious or it may cost you. I did not as I knew what caused it when it did thst. Which wss the o2 I had extended the wiring on.