idling problem.../new to here

[bigbrosyclone]

ok lil background info.. i have a 91 syclone, was my older brothers and was handed down to me..

the question and prob i have is this..

when u start the truck it idles like crap til its warm.. well when it gets warm it seems fine then after a few mins it starts to surge from 1100 to 800, constantly. but when u throw it in drive / reverse it runs likea champ.... it dont misfire.. it just idles bad. like i can be at a light and it will be fine but if i put it in neutral it surges. k well the other prob is.. when its running i try to throw on the heat and it bogs all the way down to 400 rpm and almost dying out, doesnt do it all the time tho.. very weird..

so far we changed the spark plugs / wires distr. cap and rotor ( speakin of which it wasnt timed right, we just timed it right last week) brand new iac so far

the fuel pressure also bounces between 70 to 100 quickly.. the fuel line is kinda riggged.. but still that wouldnt be makin it only have probs when idling?

so far no engine lights on.. but we run it on scanner and we normally get 45 (o2 sensor) and now last night got a code 35( dont know what that is i gotta go read the book)

im sorry for the long post.. and if this doesnt belong in this category i m sorry bout that to, the reason im so obsessed with tryin to fix this truck is cause my older brother passed away last year.. and well this was his baby, and never had the money to get it fixed.. well me and my younger brother are tryin out damnest.. if anyone can have any input on this we would apreciate it.. thanks

oh and we checked vacuum leaks and all spark plugs and injectors are good..

 

[WyoSyclone]

Re: idling problem.../new to here

Welcome.. that's a good first post - cool that you're trying to get it running for your brother.
When you say the fuel line is rigged, what does that mean? That could be a suspect area depending on what kind of condition it is in. Also, if the truck has been sitting for a long time it may not be a bad idea to put a new fuel filter on it.

Posting a little more history on what kind of shape it's in would help too.

 

[bigbrosyclone]

Re: idling problem.../new to here

haha thanks for the compliment..

ok onto the truck.. we got it repainted so body is tope shape... the engine doesnt shake alot.. only when it surging it does...
um the oriignal fuel line got smashed when they took out the engine few years back. oh and the truck mileage is 90k

so what they did was take 2 rubber 90 degree angle hoses and connect it to a little silver pipe.. like a gateway... ( sorry if im not bein 100% clear im not mechanically inclined) and they thue hose clamps on it.. well fuel used to lightly come out until we threw on more clamps to get it tighter..( worked thus far)...

but yea.. the truck is quicker then shit still... doesnt misfire (my father in law is a good mechanic and is helping me)

just that damn surgin only in park or neutral and when the truck is warm...

if u want more info i can try and get pics of the engine tomrrow or sunday and throw them up..

thanks for your time

 

[bigbrosyclone]

Re: idling problem.../new to here

ill have to get some pics up of it in general.. i love flaunting it get stopped on streets and stuff askin to sell it!!

 

[powercat6]

Re: idling problem.../new to here

Based on the fact that you have a bad idle and have negative effects after turning on the heat I would guess you have original vacuum hoses that are burned up and rotted. Replace them if you haven't already and you should see an improvement. When you're replacing them go ahead and invest in silicone hoses they're worth the investment.

 

[bigbrosyclone]

Re: idling problem.../new to here

ok... thats something ill keep in mind.. thanks
and one other thing, when we disconnected a vacuum line it still surged like that... ? we are goin to run more tests tomrrow on it so hopefully we figure something out..

 

[bigbrosyclone]

Re: idling problem.../new to here

i havent got a chance to do all the things i was gonna do but i do see other things wrong..

for one there is a crack where the hose goes into the intercooler at... leaks sometimes... i need to get that welded..
another prob im having is when i start the truck sometimes it leaks fuel right from under the driver side kinda by the fuel filter...
another problem i jsut saw today i threw out black smoke when accelerating..

i bought a new o2 sensor fuel filter so far.. i have not put then on.. due to the old o2 snsor is stuck in there so yea..

if you guys have any other ideas on whats goin on id love to hear them.. thanks again

and sorry if this post is confusing im tryin not to be

 

[alwayscode390]

Re: idling problem.../new to here

Sounds like a vacuum leak to me too ... just because you took one hose off, doesnt mean you took the LEAKY (split) hose off, heheh ... replace them all ---

 

[bigbrosyclone]

Re: idling problem.../new to here

alright will do thanks

 

[bigbrosyclone]

Re: idling problem.../new to here

ok..... sorry to post again.. but i was jsut checkin some stuff out on the syclone and i decided to see if the k&n air filter was dirty... comes to find out .... there is no air filter!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! i never knew this til now... wish my younger brother woulda checked that too... anywho... would that make it idle like crap? thanks

 

[bigbrosyclone]

Re: idling problem.../new to here

alright thats goood to know too... ii just install an air filter finaly.. ( didint know there wasnt one in there) and now its warming up... goin to see if that changes the idle... ?? but i will relay this info to my father in law.. ( he is the one workin on it with me, pretty good mechanic)


k this is an edit... i let it warm up and even with air filter it does same thing... and i have 2 ecms... 1 is the original and the one thats on there now..

i tried the original the truck wouldnt even start..? but thats cuz it was missing the chip right? cuz the one i have on there has a chip on it and the original dont..

i dont mean to sound dumb but can i take the the chip out and put it on the orinigal? im pretty sure my older brother had it set up for a 0-60 truck? if thta makes some sense


and now whne its rough idling i throw it in drive and one outta 5 times it bogs down and lights flickker on dash and dies out ..... ???? sure this isnt a alternator prob? or ground? thanks

 

[bigbrosyclone]

Re: idling problem.../new to here

if i knew how to change out ecm chips id try other one??? i very smart at computers lmao... just not car computers


i got the chip number says.... 1993 JET PERF PROD part#29119-s OFF Road ONLY!!!

lol thats what the chips says in the ecm thats on there... the ecm numbers goes as follows : service # 16198263

and on the original ecm i see 01227749.. can i take the chip out of the one thats on the truck and put it in the orig.?? will it screw it up or what? thanks

 

[midnightbluS10]

Re: idling problem.../new to here

You may want to make a post in the "Parts Wanted" section and see if anyone has an OEM chip for sale to replace that Jet Performance chip. At least you'll be able to rule that out.

 

[powercat6]

Re: idling problem.../new to here

I don't know what a 8263 ECM is. I've never heard of a substitute for the 7749.

Put your jet chip in the 7749 and see what happens.

From sytyauthority.net

ECM old GM #1227749
new GM #16198263

 

[bigbrosyclone]

Re: idling problem.../new to here

k i thew in the chip on the original... no difference... truck seems to just surg no matter what now?? weird unless i never noticed it while driving... but at red lights and what not it was fine... but all of a suddenwhen i throw it in drive the lights kinda flicker as it bogs down no matter what.. after its warmed up.... white and black smoke come out...

 

[midnightbluS10]

I don't know what a 8263 ECM is. I've never heard of a substitute for the 7749.

Put your jet chip in the 7749 and see what happens.

I have. Do a search on here for 16198263. There's a bit of info about it.

 

[bigbrosyclone]

Re: idling problem.../new to here

anothr question... i work for gm.. like ima dealer with them but we mostly do volvo semi trucks stuff..... can i get a chip or ecm from my gm dealer??? tryin not to sound confusing.. but do they still make em?? ( thats if the ecm / chip is my prob)

 

[midnightbluS10]

Re: idling problem.../new to here

I think you can get a new/reman'd ecm from the parts store. GMPartsdirect.com shows the ecm for $85 pn 16198263. They don't show anything for the memcal, though. I used PN 16181579 that I found on sytyauthority.net

841 BBZB 1580 16181579

 

[BoostedSUV]

Re: idling problem.../new to here

the fuel pressure also bounces between 70 to 100 quickly.. the fuel line is kinda riggged.. but still that wouldnt be makin it only have probs when idling?

That is entirely too much fuel pressure... it should be around 32-35lbs with stock truck.

 

[midnightbluS10]

That is entirely too much fuel pressure... it should be around 32-35lbs with stock truck.

I've always heard 42lbs with vac line disconnected. Or you can energize the pump at the test terminal and set it that way without having to remove the vac line or lean over a running engine.

edit: I believe it should be 35-38lbs with vac line connected and truck running. Trying to find previous posts to back that up, but I'm not really having any luck.