I feel realy dumb asking this question, but I have tried every D*MN thing I can think of. When you depress the accellerator slowly from idle to full-throttle, it accelerates very iratically. At some points, it cuts out completely, going right back to idle speed. (but it always works at full throttle) also, when the engine is held at this middle ground, it sometimes backfires. (can't tell if it's through the TB or the Exhaust) As you can imagine, this is extremely annoying. The weird thing is, it's random. Sometimes it's very bad, other times it's pretty mild. Every time I pull from a light, I feel like I'm in my old 4-cyl Rustang. My first thought was the TPS, but I replaced it to no avail. Next idea was the ignition, but I replaced it... no dice. Then the computer kept telling me bad MAF, so I replaced that. (idles better, but still no result) All I can think of now is that timing is off, but I thought the computer took care of that. (Also, need to reset the comp... how?) My next course of action is to replace the fuel filter and get the fuel pump and fuel rail pressure regulator tested. ANY help would be appreciated!

 

My blazer did that too, and I never could find the problem. Good luck.

 

Great! Lots of help there... Just kidding.

Did the problem just go away (yeah, I wish) or did you sell it? How did you resolve the problem is what I guess I'm asking.

 

could be your ecm...

 

Forgive me for sounding ignorant, I don't have my hayes right here in front of me... what is an ECM... hope you're not referring to the 'puter!

 

Reset ecm~'puter..disconnect battery preferably for 30 secs, reconnect, reset radio presets, start car, enjoy!

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85 Firebird. $150.00
2.8 Auto.
Blown Head Gasket.
turbo has arrived,

 

My blazer was also a 2.8 TBI so it's very possible it's not the same problem, but nope, never found it. Sold it when it was in one of it's "running good" moods

 

no computer can only correct so many degrees of timing, the way you set the timing is disconnect the white connecter on the passanger side, (can't miss it) then hook everything up, if you have an automatic you need to have somebody put it in DRIVE and hold the brake while you set the timing, last make sure you have 10* degrees timing advanced and your all set, just turn the car off and reconnect the white wire and disconnect then reconnect the battery to clear codes and your done. Fuel filter is another GREAT place to start, but finally I think it's injectors.

 

My 'bird did the same thing when I 1st got it, idle or all out but, nothing was smoothe in between, after having the FP tested it was told the pump was crap.

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• my Formula Homepage
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The mind is like a parachute, it only works when its open

 

have yo uchecked you TPS?

if you have a flat spot it can do some wierd stuff

timing.

also check the wiring near you afm if you have one

 

Thank you for the suggestions, guys. I'll start with the ECM reset, and check the timing as well... I replaced the fuel filter last night and I'm getting good pressure at the rail so... I'll let you know what's going on. (What's an AFM?) Sorry, no haynes at work!

P.S. Are you sure it has to be in gear? That sounds REALLY dangerous to me.

 

This sounds pretty familiar to me. I've got a 91 3.1 RS automatic tranny with MPFI and it has almost the same problem. Except my problem seems to be linked to the outside air temperature/weather conditions, rather than the engine temp, etc...weirdest thing. If I don't run the car for a day and run it in the afternoon when it's a tad hotter, it's fine. But if I don't run it for the same period of time and then go in the morning, it takes longer to start, it idles really hot and the fan or something pretty rapidly engages and disengages.. I don't think it's the fan, but I have no clue what it is. You just hear a click, and the rpm's run up, then another click and they fall, back and forth, almost like the compressor, which I don't ever use anymore because it's gonna seize. And my hesitation is just like the guy who posted this' is, except mine isn't quite that bad. I've replaced my spark plug wires (super 7mm's), my air filter (K&N), and my fuel filter.. The new fuel filter kept me from stalling during downshifts, but didn't fix the underlying problem. Hey, any help you can offer this guy would benefit me..so..keep it up! It's extremely irritating.. Doesn't run clear until I give it full gas, where it roars really loudly and kicks wicked hard on all of the shifts...enough to knock you back. Thanks everyone.

 

I just fixed a similar problem with a 2.8L MPFI. She had a "wild idle" problem with the idle all over the place while sitting that got a bit better but was erratic even when I brought the RPMs up some. The problem was the idle speed control, and I had to advance the idle up about 150RPM. She used to idle around 620RPM, I now have it up @ 750RPM.

I've also had the weather-changing idle / start problem as well, which I just chose to live with rather than chase down. Basically, she *hates* damp days. My last guess was the humidity screwing up what the MAF & O2 sensor read.

This is a problem you can definitely chase-the-needle on annoyingly. There's just some things you sometimes have to live with.

 

Thanks for the help guys... my post got a little off track because of that one post, so I'm going to clarify here.

The problem is durring acceleration. The car idles beautifuly. It starts great. Damp, dry, cold, hot... doesn't matter. Idle and strating are fine. When I accelerate, the car bucks and drops at random intervals. Just wanted to clarify.

P.S. moisture-related engine problems are almost always related to the ignition. To test: on a DRY day, put water in an atomizer (a spray bottle that will make a mist) and lightly mist your coil. I would bet money that the car will start acting iradically. (good ignitions do not do this)

 

You've got fuel delivery problems!
CHeck the hose used for anywhere. IF IT'S NEW, it MAY be the wrong hose. You specifically need, "Fuel Injection Hose".
It is different. Had this happen on a car, I used regualr gas line. Car wouldn't go over 35mph. I replaced a section with the wrong hose. It collasped under fuel delivery prerssure.
My problem is poor idle, then the computer kick in and bypasses the offending part, then it idles smoother. The computer keeps resetting itself, every time I start, so I know the "Computer System" is functioning properly. My code scanner points to a bad MAS or MAF (I have a 1985 FI set up) sensor.....AGAIN!!!!! Code 34
I know it's not a vacuum break. My idle goes back to 17 inches of vacuum (after the computer kicks in to overide), so I know all hoses are good.
Sucks. But, it does affect acceleration too much. So pulls real well.
I can't believe it'd be (in my case) fuel pump or fuel filter.
Why else would I get a code 34? And the computer cannot override a worn out fuel delivery system.

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Chat Soon,
KED85
Karl
1985 Firebird 2.8 to 3.4 swap project for Smog Happy LA, CA

 

Have you tried some fuel injection cleaner....It sounds kinda *DUH*. But It might help out. It would be a smart thing 2 try before you start testing your fuel pressure regulator...and etc.

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Bad A$$ Boys Drive Bad A$$ Toys

 

Well, looks like this weekend is going to be a greasy one. LOTS to do to the ol' bird! I'll let you know next week what I found out. Thanks for all the help.