Well i have my new motor in my 94 suburban...(old 350 will go in the camaro) but i have a few problems..this is what i did to the new motor...its stock LO5 other than a vortec roller cam..and edlebrock performer RPM intake with adapter for the TBI and 1.5 roller tip rockers. The cat is empty and is single exhaust with a flowmaster..the motor runs great and has tons of torque. here are the probs i have tho.

1. erratic idle when warm or cold. i did notice when the timing was on 0* the idle was better but it killed the gas mileage. when i put it on 6* the gas mileage was alot better but the erratic idle was back..by erratic i mean it sounds sorta like a miss but its not.

i was hoping to get more mpg outta this combo..the computer is stock and thats a whole different can of worms that i am not set up for. if anyone has any ideas i would be thankful...

 

Anyone that sees it necessary please jump in and correct me if I'm wrong.

If that's not a stock cam you probably need a chip to have it run well, though I don't think that's really the source of your problem.

What do you mean by erratic idle, what comes to mind for me is that the idle is fluctuating, surging and dropping. Are those the symptoms?

Does it ever stall out on you? If so check the EGR.

 

well it has an edlebrock performer RPM non-egr intake..the cam is a stock vortec roller cam..i have checked for vacum leaks..and its a problem only when in park or in gear idleing like at a red lite or stop signg etc..it never has stalled out and everything is fresh with the new motor..all vacum lines fresh pluges cap rotor and wires..

 

anyone??? i diddnt think it was that big a problem..

 

Lets take a step back.

Engine: Fresh LO5 with Vortec (specs?) roller cam caped with swirl heads?
Intake: Performer non EGR
PCM: 16197427 prom id BJLH? No mods for absent EGR?

0 degree - idle is good, lousy mileage
6 degree - idle is poor, better mileage

'94 Burban stock idle setting 0 degree, 650 RPM???

//RF

 

Yes fresh LO5 stock vortec cam. Only code is for the EGR..which i expected. PCM and chip are all stock no mods..it idles at 750 RPM.. it runs greats. just the idle thing it has going on. I cant believe the amount of torque it puts out.

 

Well i have a little time to check a few things on my suburban yesterday.. so i pulled the plugs to see how they looked and first thing i noticed that they are sno-white. they look brand new which has me thinking its running really lean..i dont have a way to check fuel pressure but i can tell you it never bangs out under full throttle or acts like its running out of fuel. i now have the timing at 2*.. i did pull the top of the injector pod and inserted a small bolt into the slot on the fuel regulator to push up on the diaphram for more fuel pressure and it seemed to help the idle.

My fuel pump is stock for the burban and is only a year old at most.. is a stock pump good enough for what i do? and i read some other posts about guys that run the performer RPM intake and they removed the divider..

anyways i am just trying to get it running better and better fuel mileage..right now i am averageing 14-15 mpg average intown and hwy...

 

Wow a real stumper apparently... so what gives ? because its not a camaro ?? this is about the only place that a few people know about TBI stuff... anywho thanks for those that tried helping..

 

cricket cricket cricket .........

 

hop on ls1truck.com they have tons of knowledge of just about any gm truck/suv!

 

The plugs mean nothing unless you pulled them after a WOT run. The PCM runs the engine around stoich, so you wont see any deposits.

At the very least, you likely need to tune the truck. The PCM in there is fairly well understood, and the tuning equipment wont cost more than around $150.

The erratic idle could be the PCM itself. These are set up to use the spark advance to control the idle speed. If the spark advance is off, it can cause the engine to idle erratically. The first thing I would try is disabling the derivative and proportional idle spark advances.

 

Well after considering all the probs i was dealing with i decided to put the factory TBI intake back on and see if that helped the idleing probs i was having.. and sure enough it fixed it and i did check the gaskets i pulled for leaks and such and found none.. but i do have a new problem..

When i was cleaning up the TBI intake i found the EGR was bad so i replaced it with a good EGR i had on another intake..now here is the problem..when the EGR opens up it wont shut and it kills the engine..the EGR isnt sticking open the vacum source keeps sucking and keeps it open..all the vacum lines are run correctly..but i am not sure how to test the what i think is some type of soleniod that controls the vacum to the EGR.. I am guessing the reason i diddnt notice this problem on the old motor is because the EGR was bad.. anyways i would be thankful for any advice on this...

oh btw it idles like a dream now..i think the edlebrock performer RPM was too much for it...beats me...

 

when you swapped to that intake and cam....you needed more fuel...and the only correct way to get it going right is to get a custom chip....

 

There three different flavors or EGR valves out there P - positive back pressure, N - negative back pressure and neutral. Depending on exhaust system design different EGR valves were installed. Take a look at your original valve - look for P or N letters stamped next to part number. Finding a replacement EGR is always a challenge.

Vacuum to EGR is controlled with EGR solenoid which is PWM by ECM control line. This way ECM can vary amount of vacuum reaching EGR diaphragm. It is not on-off device, but instead vacuum is pulse width modulated (PWM) allowing finite EGR valve opening.

//RF

 

Well i replaced the egr solenoid just to make sure it was ok..still did the same thing...now the original egr that was on the intake was a replacement and has no visable markings on it...so i am not sure on what to do next..sounds like the egr i put on isnt the correct one.. any ideas on how to find out which one i need?

 

Take couple of close up photos of original EGR valve. Make sure that the piston and overall shot are available. Use macro setting on a digital camera to allow close-ups.

//RF

 

Take couple of close up photos of original EGR valve. Make sure that the piston and overall shot are available. Use macro setting on a digital camera to allow close-ups. Plus, see links below.

http://www.tomco-inc.com/Tech_Tips/ttt27.pdf

https://www.thirdgen.org/forums/tbi/...e-headers.html


//RF

 

Wow this is great info and i am very thankful...when i get home i will check out the egr's closer and let ya know what i figure out...again thanks RFmaster..

 

Well i looked ath the egr and found what appears to be an "P" on it..its an aftermarket egr and its not exactly like either one of the pix from the links you posted..

my questoin is how do u test a positive egr? i know if i apply vacum to it that it doesnt move..?? and i have not identified the egr thats on the motor right now...i will tomorrow tho..thanks

 

hey i just got a 1986 camaro with a 92 v8 5.7 liter engine in it . the car was running really crappy so i had to change firing order on the car it was running alot better.. but still wasnt right about a week later i discovred the smog silinoid was disconnected from the terminal where it goes into the top of the engine also the electric was not pluged into the conponent. i did some research and found out the correct way to hook it up .. i started and drove the car about 5 blocks car seamed to be running better then ever smooth and more power . after i turned the car off and tryed to start it up the next day .. car does not start .. as u hold the exnition and pump the gas the engine gets slowly to full running speed as if its running and when i let go of the exnition it turnes off as quick as i let go ?? i also tryed removing the smog silinoid back to how i org found it still same story any suggestions ?? thanks

 

I dug around for couple of hours and found this.. I will post the web site and hope it helps oithers in the future..I makes understanding the EGR valve and testing them really easy..

http://www.aa1car.com/library/egr.htm