Car runs like POO! Help!

I took my car out today for it's second test drive since the Novi install. It seemed to idle the best with a tad under 40 psi so I set the pressure to 37 psi and was on my way. During the drive, the car felt strong with no detonation but when I would slow down, it would stall. This is what happened on my last test drive whith my FP set at 41 psi.

I know 37 psi is a little low but could it still be running rich down low and causing the car to stall like this? I'm afraid to back the timing down anymore for fear of detonation. Also, when I would be coasting and rpm's would drop below 1500, my check engine light would come on and the car would start to surge a little bit. I'm assuming this is related to the fuel problem.

Other than these couple problems, the car seems to run pretty good. I saw 5 psi in third gear at around 5000 rpm. It was just embarassing to roll to a stop sign and have to restart the car everytime!

do you have a bypass installed?

Yep, I have the bypass and the MAF clocked. It idled fine before I left my house. It was idling for 5 or 6 minutes without any surging but after driving for a few minutes, it would want to stall when rpm's would drop. My engine is basicaly stock except for the Novi. I have the stock pulleys on it so I'm only seeing 5-6 psi. I have 36# injectors, a 255 lph In-tank, and NO FMU.

I just moved it into the garage and it seemed to run ok for the 60 seconds or so that it took me. No surging or anything. I'll just have to play with the FP over the next couple days I guess. See what works and what doesn't. I swear, this car drives me nuts sometimes.

Ah well, it'll all pay off when I get everything situated. For now though, it's Saturday night, 60* outside, and I'm off to drink some beer. :cheers: :yipee: . The car will have to wait until tomorrow. I love my priorities. :dance:

what kind of mass air meter do you have? is it heating up at all? what is your timing set at? try putting it at 10 degress DTC and go from there...mine did the same thing..

My timing is at 11*. I have a 76mm C&L MAF calibrated for the 36#'ers. I hadn't noticed if my MAF was heating up at all, that's something I'll have to check out.

what kinda plugs and what are they gapped at ,what heat range?

have you replaced your fuel filter?

As far as the surging goes. Dissconnect the vacuum line to your bypass, take it for a test drive(DO NOT PUT IT UNDER BOOST). If the surging goes away, then you have a bypass problem. When my bypass faied, my car did the exact same thing.
Doug

Go over your vacuum system top to bottom. It might be a leak. After I put my car back together one time I goofed up a line to something, it would idle in the driveway but not very well. Not erradic but very lopey. Same characteristics as you, car would die on deceleration or would act like it would cut out then come to life after a second and have a sloppy idle while sitting at the light. Obviously it could be something else, but it sounds so much like a vacuum leak. After I found a hose that had blown off, it idled like a champ and ran so much better ;)

Man my grammar is getting sloppy on here, typing too fast I guess.

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Originally posted by Hustler
Go over your vacuum system top to bottom. It might be a leak. After I put my car back together one time I goofed up a line to something, it would idle in the driveway but not very well. Not erradic but very lopey. Same characteristics as you, car would die on deceleration or would act like it would cut out then come to life after a second and have a sloppy idle while sitting at the light. Obviously it could be something else, but it sounds so much like a vacuum leak. After I found a hose that had blown off, it idled like a champ and ran so much better ;)

Man my grammar is getting sloppy on here, typing too fast I guess.

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You may have it right Hustler. When I was detailing the engine, I broke a vacuum hose that goes right after the smog pump. Instead of replacing it, I took some extra vacuum line I had from my bypass valve and clamped it onto the broken line. I'll bet there is a small leak coming from that line. This weekend I'll know for sure.

^^^^^

Boy does that sound like a ghetto fix :D

after the car is warmed, unplug your idle air control valve, set the idle with the throttle stop screw so that it idles at about 700-750 rpm without the IAC plugged in. Ideally you want your IAC at @ 20% duty cycle to keep the stock idle of 675 but without datalogging it you are better off setting the stop screw a little high to help prevent stalling/surging. If you have a vac leak the idle should suddenly turn fairly rough if you let it sit idling for @ 2.5-3 minutes.

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Originally posted by fanglemeister
If you have a vac leak the idle should suddenly turn fairly rough if you let it sit idling for @ 2.5-3 minutes.

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Bingo! After idling very smoothly for a few minutes today, the idle started to surge a little bit...I had to give it a little gas to keep from stalling. Now I know what the problem is. Thank god it's something small. I'll bet anything that it's the vacuum line with my ghetto fix on it.

Well, I fixed the vacuum line that was ghetto fixed and I still have the same problem. The car is showing -19/-20 vacuum at idle and idles fine for a few minutes...after that, it's all downhill. I've checked all my other vacuum lines and everything looks good.

BTW, is there any vacuum associated with the a/c? I removed my a/c over the winter. Took out the compressor, condensor, and the can thing on the firewall. I just put some electrical tape over the two lines that go through the firewall. Were there any vacuum lines associated with the a/c that I could be missing? This is the only thing that I can think of. I'm kinda stumped.

Would a blown head gasket have these same symptoms?

The Stang left me stranded 6 miles from home yesterday after it died and wouldn't stay running/idling. I had to walk home. Took me 2 hours. This car is REALLY testing my patience right now.

Do you have an FPR with a vacuum port? Aftermarket chip? Did it die when you came to a stop again?

I have a Kirban FPR with no vacuum port. No aftermarket chip, BTM, or PMS. I'm just tuning it as best I can until I can get a custom dyno tune. It did die when I came to a stop (In the CVS parking lot) and had trouble starting back up and idling. I left it sit at CVS for a few hours until I could get a ride back and get it. Later that night, I went back to get it and it still wouldn't idle without dying so it had to be towed back to my house.

Today, it started and idled GREAT for about 3 or 4 minutes then the idle got real rough and it died. The idle seems to smooth out after the car sits for a few hours. I removed my driver side spark plugs and they were very dark. I noticed when I backed my timing down to 10* it idled worse than when it was at 12*-14*. I'd bump the timing back up but I don't want to without a way of pulling some out under boost.

The car starts and idles first in open loop mode and then switches to closed loop mode which is controlled by the O2 sensors. Sounds like your O2s are hosed, time to replace them. Make sure you clear out the eec computer's memory after you replace them.

If you are running pig rich under open loop, you can start to kill them within a few hundred miles.

I had to take my O2 sensors out when I installed my headers and they looked pretty black and nasty. I'll try replacing them and see if that solves my problem. I seem to be pulling plenty of vacuum so I'm not so sure it's a vacuum leak.

Could bad O2 sensors cause the 'check engine' light to come on? I've noticed that when cruising below 2000 rpm's the check engine light will come on until rpm's increase. I'm crossing my fingers....

Come to think of it, if I'm ordering some O2 sensors, why not order a F150 pulley as well :D

Whistler, how did you make out with the new O2 sensors?

The sensors are on their way. I'm just waiting for 'Brown' to drop them off. The anticipation is killing me. I really hope my problem is with the O2 sensors.

While I've been waiting, I took off the front sway bar and removed that metal hunk of crap by the rearend. Saved a little bit of weight :)

Hopefully, Brown will show up tomorrow and I can give an update on things.

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Originally posted by Whistler
While I've been waiting, I took off the front sway bar and removed that metal hunk of crap by the rearend. Saved a little bit of weight :)

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That hunk of iron is actually tuned to the rear gear ratio; once you swap to a different ratio it is virtually useless, except for use as a traction aid.:D

I have the exact same problem on my truck. When I let off the gas it surges and if I depress the clutch the revs will drop all the way to zero. Sometimes it will catch itself, not often. It idles eratically and also does it sporatically, sometimes it'll do it, sometimes not. I have looked over my vacuum's 37.5 times and even took the intake manifold off to check the gaskets. It will not hold a steady rpm, such as trying to spool up to launch, the rpms will jump all around. The MAF has been clocked to where it sort of fixed it, not totally. Where should the plug position be on it? Does it matter if the MAF get's hot? The TPS checked fine as well as the IAC. If the O2's go bad, it should throw a code and it hasn't...but it does smell very rich upon startup and in general with gas mileage out the window. And could the lack of a bypass be causing all these problems?!?! Please help before I drive this truck into a tree!

Jesse