Help! 91 L98 boggs at 3500rpm-up

[loupietrofesa]

My 91 corvette L-98 w/27k mi. boggs at 3500 rpm and up, like it is not getting fuel possibly. I have new plugs, wires, cap, rotor, coil and tps. Now at least it idles and does not stall, however it goes flat when I get on it. If I disconnect the tps it has much more power and idles smoother, but still goes flat. What can I check???

 

[93Rubie]

Welcome, to CAC, you have any check engine light on? If so, start with checking for codes.

 

[loupietrofesa]

no codes, except of course when i unplug the tps

 

[loupietrofesa]

I should add that it only does it when it is at normal operating temp, it is ok the first 15 miles...

 

[Curious George]

My 91 corvette L-98 w/27k mi. boggs at 3500 rpm and up, like it is not getting fuel possibly. I have new plugs, wires, cap, rotor, coil and tps. Now at least it idles and does not stall, however it goes flat when I get on it. If I disconnect the tps it has much more power and idles smoother, but still goes flat. What can I check???

There are a number of areas to check... fuel pump, fuel pressure, fuel pressure regulator, injectors, etc.

CG

 

[G Winter]

Is the TPS adjusted properly ?

Glenn

 

[sstearns2]

If the fuel injectors are original then they need to be replaced with the new style due to ethanol in todays fuels eating them up inside. You can ohm check them easily to see how they are doing, but if you have the originals then it's just a breakdown waiting to happen.

Also, if you haven't done so already it will help your idle if you pull the throttle body off the intake and the IAC (the thing with the big square plug) off the bottom of the throttle body and clean all the gunk off both parts.

My WAG is fuel injectors for your bogging. Lot's of threads on fuel injectors if you search.

Good luck... what color is your 91?

Scott

 

[loupietrofesa]

Thank you, I was thinking injectors...but hoping not. My 91 is black/grey int. I did not know you could adj. the tps??

 

[Dark90]

I've been chasing a similar issue for awhile myself. It actually scared me a bit when I went WOT for the first time with the TPS unplugged. Mine only has the bogging/extremely low idle/black smoke from exhaust for about 15 minutes after a cold start and then is fine after that.

Everytime I've tried to make it to a shop with a OBD 1 scanner, by the time I get into the parking lot it's back to acting perfectly normal. ad

Is there an easy way to tell if you have stock injectors?

 

[surfer93]

Clogged cats, that is what happened to my car. If you take it to your local repair shop, they should have a tester.
Else, you can tell by the color, if it is real dark or take out the o2, if that helps you have clogged cat(s).

 

[Dark90]

Clogged cats, that is what happened to my car. If you take it to your local repair shop, they should have a tester.
Else, you can tell by the color, if it is real dark or take out the o2, if that helps you have clogged cat(s).

I think you may be right on the money.

Funny thing happened today. Started the Vette and heard what sounded like someone shaking a can of bolts under the car. I've always had this issue and was told by many people that it's somewhat normal, but today it was LOUD. Started to pull away and could hear what sounded like a Harley/Lawn mower, ended up being my car.

I pulled over and leaned out of the car to look under it while simultaneously pushing in the accelerator. There was a nice big POP and a puff of grey/black smoke out of the cat area and everything went back to normal. Havn't looked under there yet, but im guessing the exhaust gases found a new way out of the cat. :ugh

Now if I could just find somebody around here willing to fabricate and install test pipes. :cool

 

[surfer93]

Tap the cats with a hammer and listen for a rattle, telltale sign of a bad cat.