Drowning after WOT! Any ideas?

My buddy has a 95 lightning(I know it isn't a mustang but maybe you can help anyway). He has a T76 turbo, 55# injectors, and an all stock longblock, etc etc.... He also has a TWEECER on it for tuning. He is running about 13 psi of boost and has a good a/f ratio(14:1 at idle,

12.3:1 at WOT and a little over 10:1 at shifts). The problem comes when he lets off the gas, the A/F spikes up to 8:1 and kills the truck. It usually takes a while to restart it and blows black smoke like crazy! Once it finally restarts, everything is fine again. I have never seen a problem like this. Has anyone had a similar experience??? Maybe he messed with something in the TWEECER he shouldn't have? Any advice would be appreciated. I know there are some knowledgable people in here and I am hoping someone may have a clue. Thanks alot Erik D. '94 white lightning
Reply to
Erik D.
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Just kick at it here. Has he looked at the fuel regulator? It is vacuum regulated maybe it is getting erratic vacuum and or is faulty. Maybe a fuel pressure check is in order. StuK

Reply to
Stuart&Janet

I was thinking about the blowoff valve... or whatever other system that he uses to release the boost pressure.

Bear with me, cause I'm barely awake here... but, the first thing that popped into my mind when I read this story was...

Lightning owner (we'll call him George) punches the throttle, spools the boost up to 13psi, and winds his truck out... as would anyone with a turbo Lightning would do. Now, George needs to stop as he sees some red + blue lights in his rearview mirror. George lets off of the throttle immediately and hits the brakes.

There's 13psi of air waiting to go into the engine... and the throttle plate shuts. The air has already been accounted for by the MAF meter... the computer says... hey... lots of air here... we needs lots of fuel, and opens the 55 pounders up. The blowoff valve, in the interests of the engine and turbo, opens up and releases the air back into the atmosphere. Now you have a huge amount of fuel because the MAF requested it, and no air to mix with it.

George floods his engine with fuel (55lb injectors don't need much time to do so) and has hard starting issues. Black smoke pours out of his tailpipes on the fine police car behind him. George's plugs are now fouled up pretty good...

Now, that's just my guess at what might be wrong with George's truck. I'm not familiar with the TWEECER, but if it has a real-time mode, what I'd do is cause the problem and watch the MAF meter signal. This is what creates the demand for fuel.

Stu could be right, or it could be a combination of things.

Imagine if it was the throttle position sensor reading a bit high... coupled with the MAF reading the false air that exited stage right when the BOV opened up... combined with a spike in fuel pressure caused by an errant vacuum signal when the throttle is suddenly shut while in boost...

Good luck to George, and yourself... as it sounds like you'll be part of the solution.

I'm going to bed now. Goodnight all...

JS

regulated maybe it

in order. StuK

Reply to
JS

I would be willing to bet it is a problem with the blow off valve. Letting off the gas real quick like lets the air that has already been metered back out of the system while the fuel that has been measured out for that air gets dumped into the engine. Flooding, dying, then hard starting with lots of smoke could very easily occur.

If he is having problems with the blow off valve, I just happen to have some really trick ones that work great. Last one we put on a car was backing off almost 30 psi with no problems. Turbo Talon AWD hitting 28 psi at the finish line and letting off the gas caused no problems. Of course that isn't all directly related to the BOV, but can be a concern.

Let us know what you guys figure out. I would use the real-time data logging of the Tweecer to check the a/f ratio when you lift off. The MAF reading should tell a story as well.

Don Manning

Reply to
2.3Sleeper

That sounds almost exactly like what I said while I was half asleep. I'm impressed I could think that far into it. :-)

So Don, you've worked with turbo DSM cars, eh? I'm still looking for a good

2g turbo AWD Eclipse, not modified, for a project of mine....

JS

Reply to
JS

I have one for like $3500. Upgraded turbo, timing belt, new paint. Drives great, needs some interior work. I might can even come down on the price.

Don Manning

Reply to
2.3Sleeper

It's an Eclipse, not a Talon, 2g AWD? Preferrably 5-speed but an auto would be ok. Gotta look good on the outside, I can take care of the inside.

Is this your car, or a friends? I'd like as much info as possible... and where you're located, though that's not as much of a factor if it's a nice

2g Eclipse that runs well for that price....

E-mail me at snipped-for-privacy@nospam.bellatlantic.net removing the obvious...

JS

Reply to
JS

I will see what I can find out tomorrow. However, it has the 3g turbo on it now. New paint. I am sure you are familiar with the black on red paint scheme. Red body with the black spoiler that has the lines extending down to the door. Well the new paint job is basically the same, except the pain line goes all the way down towards the front of the car now, with the hood being black as well. It really looks a lot better then the original design.

Anyhow, I will see what I can find out tomorrow. Maybe grab some pics for you.

Don Manning

Reply to
2.3Sleeper

Don,

Find out everything you can about the car and let me know either here or at the e-mail address posted earlier.

Just out of curiosity, is this your car or someone else's that your trying to sell?

3g turbo... hmm... not real into the lingo of the specific turbos (people keep asking me if the Garrett T-*insert number here* is a good choice and I have no idea). By 2g I was talking about a second generation (95-99) car. I know the third gens didn't come with an option of a turbo, and in my opinion, they killed the car completely when they didn't offer the AWD turbo option. My friend's '01 GT Eclipse is a *nice* car, and it might be relatively quick, but my '89 turbo Probe with 120,000 miles on the clock will eat it up, even though he won't admit it... anyway, I'm specifically looking for a second generation Eclipse that looks and runs good, and low mileage and stock as possible. I'm not afraid to pay for it either, but if I get a damn good deal on something that needs a bit of TLC but is in good condition (like you said, interior work, etc)... then I'm on it.

JS

Reply to
JS

OK guys, thanks for the help. I found out that he isn't using the Tweecer, but it is an EEC tuner, which is supposedly not quite as good as the tweecer, but still pretty good. He is also still speed density, so that is making it a little tougher to tune. Before he went to the

55# injectors, the truck did the same thing with the 19's but it didn't dump enough fuel in to kill it like the 55's do. He's been playing with it a good bit, the truck is fast as hell, but it is still killing. He is making progress though because now it starts right back up after it kills. Before it took 5-10 minutes to get it started again. He is thinking that its something to do with limp mode and the O2 sensors. I forgot how he explained it but it made sense, so he is going to try something with that later today. I will keep everyone updated if you are interested. Don, what kind of blow-off valves are you using?? The one he has is a vortech and everything seems to be functioning properly on it, but i will let him know that it is something to look into. Thanks for all the advice guys!! Erik D. '94 white lightning
Reply to
Erik D.

The BOV's we use are home made and work great. Oh yeah, the only cost about $10 to make with parts from a hardware store.

Don Manning

Reply to
2.3Sleeper

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