secondary injector problem?

[la.farmer]

Hi everyone, I have a red/red 91. I recently replaced the injectors,removed the secondary system and installed a haibeck chip for the secondary removal. The car cranks and runs great until it warms up, then it starts stumbling very bad. If I turn the power key off, it immediately smoothes out. If anyone has ideas I would greatly appriciate it.

[tomtom72]

Hi & welcome to our corner of the world. :hello:

Since you didn't mention anything about a SES light I figure it's not throwing any codes, right?

I do believe that on a 91 Marc's chip is a default power always "on"....but I'm not sure if that applies in the case of deleted secondaries. Therefore, have you checked the actual power switch that it may be a source of a short?

The only other thing I can come up with from my limited knowledge would be that upon entering the "closed loop" stage ( you said when it warms up it stumbles ) one of the sensors is / could be sending bad data to the ECM causing a change in the fueling, or the DIS box is getting funky with the spark signal....but without any DTC's I can't have much faith in that answer.


I should shut up now because I have very little experience with secondary delete systems. Sorry I'm not much help. :o

:cheers:
Tom

[XfireZ51]

Are we talking about idle, cruise? Can you be more specific?

[la.farmer]

Its at cruising speeds. The more gas you give it the worse it gets.but as soon as I turn the power key off everything is perfect.

[XfireZ51]

When you say you "installed a Haibeck chip" for secondary removal, does that mean you bought one directly from Marc and sent him your original calibration? It sounds like your drowning the motor with the secondary injectors turned on, which the NORMAL position will turn off. I am also assuming that you removed the secondary throttle blades and shafts, correct? Any other mods to the motor?

[la.farmer]

I bought the chip straight from mark. I did remove all secondary parts except the shafts. I'm going to give mark a call to see what he thinks.

[la.farmer]

I forgot to mention that I installed rebuilt bosch injectors and new delco coil packs. Other than that everything is stock as far as I know.

[la.farmer]

Just letting everyone know, I think we solved the problem. It must have been a bad electrical connection. I pulled the plenum, cleaned and greased all the connectors under there including the injectors. Drove about 30 miles. Everything seems ok. Thanks for the response

[VetteVet]

Brian,

Glad to see that it looks like you've got it fixed. I hope that was it. Just for reference, did you find any specific connection that was loose or bad?

Jep

[la.farmer]

jep, i really couldn't tell which one wasn't connected well. i just disconnected them all, cleaned and reconnected. just got back from a 60 mile trip and it ran perfect. so hopefully that was all it was.

[Paul Workman]

http://i185.photobucket.com/albums/x220/6PPC_bucket/VeddyIntadestink-1.gif

I have Marc's sans secondaries chip as well. I was thinking that the power switch was programmed "on", as the fueling depends on the secondaries being there...No??? Hmmmm.... I'll have to "axe" 'im 'bout that next time we meet.

Anywayz...Glad you ran that gremlin down. After a couple of "no problem found" reports from the Corvette shop where I bought my first Vette, I bought a scanner and fixed the problem myself. Never been w/o a scanner since, and it has paid its worth many times over.

P.

[la.farmer]

Paul,
My chip is programmed on, but you can still turn it off with the power key.

[Paul Workman]

Paul,
My chip is programmed on, but you can still turn it off with the power key.

I checked w/ Marc yesterday. For the 90 (like mine) the switch is to remain in the FULL POWER setting always, for all driving. However, it is still functional, and the secondaries can be shut off with the key.

For the 91-95s his sans secondaries chip changes the default so the switch comes on in FULL POWER at startup instead of NORMAL; you have to manually switch it back to "NORMAL'.

When I installed my sans secondaries chip, Marc warned me that for any reason if the FULL POWER mode was shut off - intentional or by some fault prompting the ECM to make the switch - I should consider it in a "limp home" mode as the engine would be running very lean. However, in discussing it more yesterday, he has reason to believe it might not be as big a concern one might think, far as going lean goes. Apparently, the ECM has some lattitude in spite of the secondaries not running; enough so as not to be quite the :jawdrop: he thought it would be.

While I had him on the phone, I asked him if there was any liability as far as running sans secondaries where emmissions testing was at issue. He said the swirling effect inside the chamber, set up by the secondary runner being closed, is lost in the sans secondary setup. So, if your car fails by some very small percentage, and you didn't want to reinstall the secondaries (or can't if that be the case) then one might have a gasket made that would simply close off the secondary runners during the testing.

Just some FYI stuff...

P.