Spent the weekend doing my intake and EGR valve .What a difference at first.The car ran better than it ever has for the first 1hr I drove it.I ran it through the paces and it was great.After I came home I was sitting in the car and noticed a little miss that would buck the car.I never felt that before.I went back and re checked all my connections cleaned them up and decided to go out on the road.

About 15 min into the ride it started breaking up really bad under light to medium acceleration.I was worried about making it home it was so bad and got worse over time.If I kicked it down it would clear up and it would hold speed.If I gave it the slightest throttle it would buck like crazy.Came home and found I had the Pass side vacuum lines on the opposite tangs but I did not think that was it.Took it out again and it ran better for a while (about 5min)then started doing it again but a lot less bucking and missing.I seems to be throttle related to me.

Funny thing is it idles as smoothly as ever in park.Holds speed too.When it is running right it is smooth and torquey.It will accelerate under WOT with no problem.During the last year everything in the fuel system is new,O2's,Wires,plugs, replaced,TPS replaced,Dynaspark,and as I said new EGR and intake gaskets.Does anybody have an idea where to look on this?It really bummed me out did a lot of work for 1 good hour and now it sits and I know I have a problem that will keep it close to home now

No codes and I am at a loss as to what to look at on this one.One other thing is I filled up with gas just before this started.Could bad gas cause this?

C'mon guys I need some Ideas

 

If the car seems to be running good when cold and then starts hesitating on acceleration when warming up and gets worse as it gets hotter...I'd have to say the coolant temp sensor. I went through the same thing little over a year ago..chased that demon all over and finally replaced the $7 CTS...all has been well.

 

Curious top see how this plays out, going through something very similar myself.

Wheres the Hippy and CFI show?

 

OHHHH NOOOOO!!!!!

 

I have a couple of ideas. First the EGR is supposed to work only off idle and would make your car run very rough like you said. Could be the EGR, solenoid(how do you spell that?), or the temp switch that is in line with it. I had a strange problem years ago when I used too much teflon tape on a temp switch, the switch was good but the ground wasn't getting through because I used too much teflon tape. Not to say any of this is what's wrong with your car but I would start with the things you've touched recently and go from there.

 

Coolant sensor check time I guess but watching the gauge it shows no problem.This all started out with a slight hesitation when accelerating under light throttle then I got DTC32.I figured it was the EGR causing it but mabey not as it has definately gotten worse.I have gone over everything I touched and see no problems and as I said it ran great for a while.If I did not have the Dynaspark I might think it was an opti cap problem.I am trying to remember anything in my past that that caused anything like this and bad wires come to mind but mine are new and it would not deteriate this quickly in the matter of a couple of days.I only say this to describe what I am feeling.It is definately throttle related so I am still looking for suggestions.

 

Check the vaccum line to the optispark, there is a vaccum RESTRICTOR yes RESTRICTOR valve in there. If the engine is getting TOO much vacuum it will cause the problem described. Easy way to test is to remove the vaccum hose from the opti and test drive...should run ok without line. If that is the problem fix the line.

 

Will try that with the hose.One other symptom that occured at the beginning yesterday was when I was doing an acceleration run from a stop when I punched the gas it bogged big time out of the hole,almost stalled.This was after a few other runs that were OK.

 

Removing hose had no effect.Obviously I am looking at what changed and the EGR is still a suspect although I would suspect a problem at idle if this was affecting anything.

 

You have asked for suggestions and here is one for you. Make a posting on this forum asking for someone (fellow Forum member) in your area who has ECM scanning software. Request/pay him to run a scan while you drive and the data will indicate the problem. Otherwise, you are going to throw money/parts at the car with the hope that you get lucky and find your problem. Once you see scan data on your car perfromance, you will be amazed at the capabilities of this process.

 

My car has been having some of the same problems when accelerating. It bogs down and doesn't respond immediately. It all started when I topped off the radiator with the Preston 50/50 premix. It said you could mix it with any color. Plan on flushing it this week but I think it's the fuel pressure regulator. I had the same problem with my 300zx. Replaced the fpr and all is well.

 

Already ahead of you Sam I am charging my laptop right now and am going to do a Datamaster scan when I get home from work.Do not intend to throw money at it as I only have a couple of sensors that are not new.

Now back to my original question could bad gas cause this?I ask this because I filled up with Sunoco 94 yesterday before this all started happening(of couse after the intake/EGR swap) and several years ago I got a bad tank from this place.It is the only place in town with above 89.Reguardless I am letting the car run and plan on refilling elsewhere.

 

The FPR was changed in Feb.Not that they can't go bad but they usually go out over time not as rapid as this has occured.Will keep it on my list though.With as bad as it runs I would expect a DTC if any sensors were flakey but I will see.

 

Very much so, it could be bad gas. As in bad gas with lotsa water in it, maybe not dirt. Way to find out is, even if you're not down to half, put in a couple bottles of iso dry. Comes in red bottle. At the very least, it can't hurt. Do it at gas station and then fill up as much as you can to mix it as best it can be done.

 

Put the Iso in no change so rule out gas.

 

The gauge is run by the sender, not sensor. The ECM uses the sensor.

 

When you did the "EGR" did you also replace the EGR Solenoid valve and the vacuum harness assembly?

You could have an issue there. When I got that error code instead of doing all the vacuum testing I just order all three parts. BTW the vacuum harness assembly is discontinued but I believe I know where you can get one.

You say it bucks and surges as it gets warmer and up to temp, progressively getting worst, you might consider a heat soaked ECM. I had a similar runability problem and finally isolated it to the ECM which when I remove the cover plate to swap the PROM you could smell burn electrical parts.

 

I though the digital gauge runs off the sensor am I wrong?I rarely look at the analog except for Oil pressure.Anyone else have this trouble and solved it?

 

Careful, you're talking to the sensor/gauge expert.He has looked at his 8 year older Camaro and determined that ALL GM cars have to be the same.

I'd love to confirm your suspicions, Redeasysport, but my expertise on that subject ends with 1989. For what it is worth, I believe you are correct.

RACE ON!!!

 

I replaced the EGR and solenoid.Which harness are you speaking of?The car actually ran better with the old EGR after this problem started.But it ran great for some period of time till it started acting up.It will still run fine if the throttle is more than 1/2(approx) or less than the "Sweet spot" that the problem occurs at.From there to WOT it is great (much better than the old EGR) I know the engine turns off the EGR at WOT so that could be something but it sure feels like a dead spot in the throttle band.The issue with stomping the pedal at a stop and having it bog has never happened before last night.It keeps changing too I can still feel the flutter in acceleration under light throttle but it is much improved over last night when I could see my self walking down the interstate after it died on me,in the rain no less.

I will do a Datamaster scan tonight and post it here after I get a look at it for those with Datamaster.But keep the ideas coming.I wish I could find my old TPS as I replaced it for general maintainence to swap out to eliminate it.It is the only thing I can think of right now that could cause this and not throw a fault code.