Help! Humm...

[Gobbles]

Okay, here's the deal. I had my manifold gasket's replaced about a week or so ago because she wouldn't pass inspection with such a huge exhaust leak. Well its fixed now, but I've got a problem that seems to have multiplied.

She starts fine, but during normal driving and when pushing my foot through the floor board, she seems to want to die. I dont know if I need to get the honey comb, or just a get a new exhaust put on it. Or if its the fuel pump. Kind of lost on this one, and help would be great. Thanks for reading...If you have any questions, please ask and I'll ellaborate as best as I can.

Tim

 

[rlg]

Make sure they reconnected the O2 sensor. It's on the drivers side on my 90 .

Has the check engine light come on?

 

[Gobbles]

No check engine light, but I'll check the 02 sensor and let everyone know... Thanks for the help...

 

[Gobbles]

Check engine light came on, but here are some more issues...

1. Car starts up fine when cold, but once warm will idle fine, once gas is pressed, car wants to die...
2. Car fails to start once warm..
3. Also experienced some over heating tonight as I was driving at 5mph to the gas station because I had to let her idle all the way there. Not real fun when a mustang drives by, pushes in his clutch and rev's his engine. Really wish she would have came to life at that percise moment!!!

Any ideas and thanks for the help.


Tim

 

[dogfish246]

The best thing to do is get the error code from the car's computer. It will narrow down the search big time!

Do you have a code reader or scanner? If not, it is well worth it to get one ($100 for a cheape, $300 for a scanner). It works on all obd II cars 1996 and up. (I forgot to look for your year but they also sell connectors that work with OBD I ports too!)

There may also be a way to get the codes on your dash if your car is older than 1996.

Good Luck!

 

[tonylong]

This seems to be a common problem lately. Injectors? Are you using Ethanol fuel? Some years of Vettes using Multec injectors are not ethanol compliant. Mine is one of them, yours may be too. Your symptoms are nearly identical to mine. I'm having the injectors replace and general checkup done next week. Get the Injectors from Jon Bonner at FIC. He'll know the right match for your car.

 

[Fullback32]

This seems to be a common problem lately. Injectors? Are you using Ethanol fuel? Some years of Vettes using Multec injectors are not ethanol compliant. Mine is one of them, yours may be too. Your symptoms are nearly identical to mine. I'm having the injectors replace and general checkup done next week. Get the Injectors from Jon Bonner at FIC. He'll know the right match for your car.

Interesting about the ethanol. You know I had the guy at our local Corvette center tell me the same thing. As a non-mechanic type (I just like to drive 'em), I followed owner's manual and put in Premium in the '89 I just bought a little over 2 weeks ago. I called the guys over there about a rough idling prob as well. IN addition to making an appointment to get it checked out, he advised me to NOT use Premium here in Colorado as it has a high level of ethanol and that regular 89 octane would actually be better because of a lower ethanol content. I'll talk to him about the injectors you mentioned. Thanks for the tip!

 

[rmagee7]

cat. problems? had a 87 elcamino that had a plugged cat acted the same way,finally blew the cat ran fine after that

 

[rlg]

Speaking of the cat, does it smell like rotten eggs?

85 Elcamino had the problem, smelled bad, no power at all.

Check your injectors with a meter.

Should read around 16.4 ohms.

Check the fuel rail pressure, it should be at 42 with the key on.

If only 1 injector reads low zap it with 12 volts from the battery. It usually wakes it up.

 

[rlg]

Dogfish has it right.

On the 90 vettes you can use a paper clip to jump the pins on the aldl connector and read the codes. It will help you determine where the problem might be.

Do you have a FSM?

 

[seajayiii]

I would definitely have the fuel injectors ohm tested. My '90 coupe did the same thing following some seemingly minor fixes (EGR valve, new vacuum lines, new plugs ... that sort of thing). It quit on me at the Mall. It would start, but ANY pressure on the gas pedal would cause it to die out. My first thought was the fuel pump, but no. It ended up being the stock Multec injectors. If you search around, I know there's a video that explains this in some detail ... it even shows how to ohm test the injectors. And I agree with an earlier post ... Get the Injectors from Jon Bonner at FIC.

 

[Gobbles]

Dogfish has it right.

On the 90 vettes you can use a paper clip to jump the pins on the aldl connector and read the codes. It will help you determine where the problem might be.

Do you have a FSM?

Yeah, I have a FSM. I also noticed that there are two lines that come out under the TBI that seem to have been cut. They are located next to the throttle connector on the TBI. Not sure if those two were cut, but just an observation. Investigated, and seems the smaller (diameter) line connects to something underneath the TBI and above the engine...As far as the injectors, if anyone can get me in contact with (Forgot Name) that would be great.

Update: I can start her, but she starts to rough idle and then studders and finally dies... Seems as though she's not getting fuel (Injectors) but I'll check the exhaust and see about the honey comb. No rotten eggs smell....yet....

Thanks guys for all the help. I had a feeling the injectors are the main culprit, but thats just a hunch. As far as the gas goes, I never thought that it would be (too rich/not rich enough) due to the ethanol content. Maybe I shouldnt run premium. Thats the only thing I've put in it since I bought it. The guy I bought it from said he only put in 89 and it ran fine. maybe I should switch back?

Also, when I was driving down the highway to the gas station, I noticed at the end that it was starting to over heat, could this be due to injectors/rough idle?


Alright, enough complaining for now. Again, thanks for the help thus far. And I'll keep you guys posted and asking questions as they come along.

Thanks again...

 

[G Winter]

Plugged cat will cause overheating.I notice you said after you installed the exhaust gasket it seemed to take a turn for the worse. This makes sense if you have a plugged cat/cats. You had an escape for the exhaust before. Also a plugged cat usually gets more restrictive with heat for some reason so as it warms up it will run worse.
A vacuum gauge on manifold vacuum port will tell you a lot.
With gauge attached run engine at about 1500 to 2000 RPM.
Lock in the position of the throttle do not move it. Watch the engine speed and vacuum if they drop and engine even dies it is a good indication of plugged exhaust.

Glenn

 

[rlg]

What kind of lines are you talking about? Wires?
are you talking about the throttle positiong sensor?Or the cable connection?

 

[rlg]

It is also legal to remove the pre cats on the 90 vettes if that turns out to be the problem.

 

[Gobbles]

Okay, so I just got finished checking the Fuel Pressure at the rail. Got 42 psi, which is within tolerance (41-47). So I'm thinking the injectors are okay. Whats next? Any help. I'm sort of lost on this one...

 

[G Winter]

That only tells you that your fuel pump and regulator are ok.
To check the injectors you need to do a leak down test and check the ohms if you haven't.

A lean mixture can also cause over heating. I would check the TPS and the Map sensor . Both could cause stumble and lean mixture. I think in the FSM it says something about MAP sensor if starts but stops.

Glenn

 

[Gobbles]

Yeah I did the check on the MAP, calls to unplug and start car and see if problem goes away. Problem didn't go away... So I was thinking the TPS, but the FSM doesnt say how to check it, or if it does, I can't find it. Only thing I found on the TPS has nothing to do with adjusting it. Not sure if you can adjust it. But keep in mind, if i apply gas, engine stumbles and then dies automatically...

 

[tonylong]

Yeah I did the check on the MAP, calls to unplug and start car and see if problem goes away. Problem didn't go away... So I was thinking the TPS, but the FSM doesnt say how to check it, or if it does, I can't find it. Only thing I found on the TPS has nothing to do with adjusting it. Not sure if you can adjust it. But keep in mind, if i apply gas, engine stumbles and then dies automatically...

My 89's fsm does say how to check/set the tps, but it's in a strange location. You may need to go thru the fuel and electrical sections page by page to find it.

 

[Fullback32]

Just had my '89 with rough idle problems checked out. Definitely an injector problem. Two of the injectors were off as much as 10 ohms! No wonder why it died 5 miles before I got it to my 'vette mechanic. I was having the same symptoms: rough idle, then as it got warmer here almost any pressure made it die. Having the injector changed out. Ordered them and should be in next week. And it's such a nice nice weekend for driving the 'vette! Dang.