OK, just bought the car last week. PO said that it needed the EGR cleaned because it would stutter and stumble sometimes. I drove it last week with no problems. Friday driving home it threw a code. Checked the code and it was 32. I took the EGR off and cleaned it up real good while I was in there I cleaned the throttle body, changed the IAC and visually inspected the vacuum lines. Put it back together and took it for a test drive and it ran great. No shaky idle, no stumbling. Drove it to work yesterday morning and it was running great. Got home still running great. Wife and I got in it to run to Lowe's got about 2 miles from the house and it started acting like it was running out of gas. I gave it more throttle and it picked back up. Then it just died. I coasted it off the street and it fired right back up. Went on to Lowes. Looked under the hood in the parking lot to check all the lines and stuff for the 50th time since I'd put it back together and everything was fine. It stumbled and had the shaky stoplight thing going on again on the way home.
No codes thrown this time.

I am going to grab a fuel filter on the way home and try that. But I just wanted to see if you all had any input on what else I should look at. I'm thinking that it might be injectors...

It's a 90 L98 auto 125K only mods are some sort of aftermarket exhaust (non brand name) and PO told me it was chipped. He also told me that the plugs,wires and cap have about 20K on them.

Thanks for reading my really long post...and for any suggestions.

Jeff

 

What is the fuel pressure?
If you don't own a fuel pressure guage, you will need one. Preferrably with a longer hose so you can tape it to the windshield and view pressures under different driving conditions.

 

Jeff, it definately sounds like a fuel delivery problem.

Your best tools right now would be,

1. FSM from Helm's (nearly impossible to properly diagnose without).
2. A laptop with a data logging program.
3. Search feature on this forum.
4. Lots of patience

Since cleaning the EGR, did it throw a code again? The EGR uses a solenoid commanded by the ECM check it for proper operation.

After that I would check the fuel system pressure and ohm the injectors both cold and hot (the oem's are prone to failure).

I don't think it is your prime problem, but check that your plugs are not fouled and are of the correct application.

Also, the CTS input is used by the ECM to determine fuel delivery, check it also.

Good Luck and keep us updated.

 

No more codes so far, just the stalling. The service ABS light did come on though.



I have a FSM and read over it some last night trying to figure out where to start but I figured the real world experience that everyone here has might be helpful. I also used the search function and spent an hour reading up on all sorts of possible causes...almost had me scared to continue reading.

I am going to pick up a pressure gauge today when I get the fuel filter. I do want to get the cable to use my laptop for datalogging.

I had the battery disconnected while I was working on the EGR and the part that was odd to me is that it seemed like once the ECM got past the "learning period" things went funky.

 

Jeff, seems like you are doing the right things. It can seem a bit overwhelming I know. Stick with it you will get it sorted out.

Get the fuel pressure numbers, key on, engine off and while running. Then shut engine off, see how she holds pressure.

Also like Pete K. suggested, tape your gauge to the windshield and see what readings you get under different driving / load conditions. Its safest to have someone ride along to watch the gauge so you can watch the road.

 

I got the pressure gauge and fuel filter while out to lunch today. I'm thinking that it's probably the filter.

What part of PA are you in? I grew up in Stroudsburg.

 

Ok, I changed the fuel filter last night and took it for a ride just to see if that helped. It ran fine. I did find that one of the vacuum lines going to the cruise diapraghm was split so I cut the end of to a good spot and put that back on. Drove it to work this morning and it ran ok, still a rough idle. Went to lunch and it tried to shut down on me when I pulled out of the parking lot. It would be fine if I kept my foot off the accelerator but would fall on it's face if I even touched the pedal. It eventually worked itself out and sparked back. Ran ok the rest of lunch. Then tonight when I left work it was ok until about a block away then it sputtered then died. Fired right back up. Got back on the road and about 3 blocks later it was dying out with pedal again. Almost shut down on me again. I thought maybe the gas gauge is reading wrong so I put more gas in it. It managed to act well enough to get me home.
I got home and checked the voltage on the TPS, it was reading .6 volts - 4.5V so I loosened the screws and pushed it down as far as it would go and got it to read .55v

Then I ohm'd the injectors...only 2 of them gave me a reading of 17. 4 of them read 11 and the other 2 were like 9

I'm thinking it's time to get with FIC and order some new injectors.

 

Sounds like exactly what my 90 was doing before I changed the injectors.

 

Just placed my order with FIC

 

Did you ever check the fuel pressure? It could be your pump is going bad. I would check it before I replaced the injectors.

 

I did not check fuel pressure yet. I had about 20 minutes to dedicate to the Vette last night and my buddy who had a multimeter that would read the voltage at the TPS accurately was there helping me with some house projects. So I tested the injectors. Since they tested bad I figure it can't hurt to replace them.

 

Do the fuel pressure check before proceeding.

 

I already ordered the injectors but I will probably check the fuel pressure tonight.

 

Fuel pressure is 36 at idle and does not fluxuate much when I rev it up. It is sitting at 40 right now with the engine off.

Took it out for a ride with the gauge stuck under the wiper. The pressure stayed rock solid at 38 even under acceleration. It did the bucking thing like it has been with no change in the pressure.

 

Fuel pressure looks good. Looks like you narrowed it down to the injectors. Be sure to post your results after the new injectors are installed

 

I hope so!
I will post results.

 

If anyone is still reading this thread...I don't think I do but should I put sealant on the plenum gaskets when I put everything back together?

 

It is not necessary.
BTW fuel pump is easy to replace in theses things and cheap insurance.
I replaced mine along with the filter for less than $100.

 

That might be next weekends project.

If the injectors cure the current issues I'm having.

Thanks!

 

Oh if you haven't replaced the fuel pressure regulator diaphragm you might want to while its apart. Mine had to be replaced soon after I had it all back together. Talk about Pissed