Hi,
Ive been reading alot of stuff about this swap & still cant get this to run, could it be wiring or something else i overlooked?
Does any one have any tips on wiring the '04 GTO into the '91 harness?
I have the '91 stock 700r4 built for racing w/ all the upgrades & the "Bowtie Overdrives" "tv made easy" kit instaled & on the intake is a K&N cold air kit w/ SLP 5 wire maf/iac, everything should be ready to go but its hard to start & when it starts it revs up to about 1800 orso for afew and then dies & i'm getting some interm. backfiring from the exhaust (black smoke) that smells really rich.
Ive tried afew ideas from posts on this site & others but still no luck, any help would be greatly appreciated!

 

Have you tuned the VATS out of the PCM? and have you bypassed the car's VATS?

 

The pcm was just done by "wait4meperformance" no vats on the car itself, the motor starts & runs rough for few & then dies, I forgot to say that I dont have the o2 sensors in yet because i hafto get the bungs relocated, would that be part of the problem here?
I was told LS1's have a "limp home" mode incase you loose your o2's on the road, & that they will run w/o them for a while, is this true?

 

sounds like VATS isn't tuned out of the PCM.

 

I'm not sure on the O2's, IIRC the engine will run without them but i'm not 100% sure. Have you checked fuel pressure?

 

I thought it woudnt start at all if the vats was on, but he said thats one of the first things they did when they reprogramed it.
I havent checked the fuel pressure, but its a new walbro set-up in the tank & steel braided lines upto the rails so it s/b good there.

 

O2 sensors dont cause the engine to die. Mines arent plugged in yet and the engine runs almost flawlessly... VERY rich but great idle.

Im guessing VATS too.

 

The car will start with VATS in, but it will shut off after about 5 seconds when it runs out of gas due to the fuel pump not running.

 

does that still apply if its a "stand alone" pump, not pcm controled?

 

+1 for VATS

O2s are not even registered until the engine is warmed up. Even unplugged/missing they shouldnt cause it to stall out

 

ok, so what about the rough/ crazy idle & backfire?

 

you can be able to get that engine to run without the 02's and the maf. it wont run good without the maf. but it will run. as for backfiring that is another issue.did you do anything to the engine before you put it in. yes there is a limp home mode but it would keep running. vats i dont think will cause a rich backfire issue. have you tried to see if you loose spark or power to the pcm. sounds as though there is an issue with fuel or timing.

 

I only changed the oil pan & maf nothing else

 

is the cam sensor any good. is it plugged in? check both.

 

its plugged in but how do you know if its bad or not?

 

about the only way is by a code set or to replace it. is it setting codes at all.

 

Try replacing it with another one, if it doesn't fix it then just take it back to the store and keep trying other things.

 

also make sure you have both coil pack sets plugged in.

 

What are you using as your ECM? And where did you get your tune from? The description below...

...sounds to ME like the tune is off. "Hard to start"/"backfiring" sounds like timing. "Revs to about 1800" and "(black smoke) that smells really rich" sounds like either the fuel curve or injector constant is outta whack. The only thing that would affect both (unless I'm missing something - which could be, it's kinda late) is the tune/ECM.

It wouldn't be a bad idea to double-check the fuel pressure at the rail as well, just to be sure.

Good luck.

 

I have the orig. '04 GTO harn. moded for stand alone wich (I think) is hooked up right according to my instructions from the seller also I just called "wiat4meperformance" who did pcm & they said its deff. not the vats or the fuel/ spark curves, they stand by their tunes 100% so they said to re-check all grounds & wiring, pull off the maf & get the o2's in, so thats whwt I'll try next I guess. iduunno, feels like I'm just graspin at straws here?

 

CRAP. I KNEW you were going to mention that name... Myself personally, I wouldn't give a squirt of cold urine for one of his tunes - or his "customer service". I know that a number of people have come away with cars that run OK after having that outfit do the tune, but from everything I've read, it's pretty much a crapshoot.

I don't suppose you know of anyone fairly near you who has EFILive (or something similar) & could look at the program in the ECM?

 

well i wasnt going to say anything about waitformeperformance. but if it is locked you might not be able to read the tune.it has to have set a code by now.

 

SO THEY CAN LOCK IT SO IT CANT BE CHANGED? OR JUST LOOKED AT AGAIN, LAME!
SO WHAT YOUR TELLIN ME IS THAT I JUST GOT SCREWED ON THAT TUNE JOB & I SHOULD PAY SOMEONE ELSE TO DO IT AGAIN!

 

i had a good friend who went to wiat4meperf. & his was great! thats the only reason I went there.
so i should send it back to be redone or find someone else & pay more? i dont get it why is it so hard to find someone to program a pcm right?

 

yes a pcm can be locked. they do that so someone else cannot read there tune. i used to tune my 02 silvy with hp tuners. i was taught by some that still tunes today and is pretty darn good at it. yes they lock them. from my experience on another board which was performancetrucks.net he had a bad wrap.

no it doesnt mean you got a **** tune at all. but i would send it back and have them check it. all they know is at the end of loading it says tune was succesful. they did not test it.

 

I agree that it sounds like the tune is off sum how, too much fuel not enough spark or sometin along those lines, but I really dont want to send this back again! WTF!
should i just go back to stock w/ the fuel & spark parameters or do I need it tuned for altitude?
I'm still gonna check fuel pressure@ the rails & see if thats off any, it shouldnt be cuz i have a new walbro pump, but none the less I wanna do it just to know 4 sure.

 

Going back to stock might not be a bad place to start from - and you don't need to have it tuned for altitude - I'm at altitude also & as long as you've got a working MAF sensor, it'll tell the ECM how much air there is.

(Yes, I KNOW you can also do a speed-density tune, but that's just a "semi-educated" guess, & not especially helpful up here where you can go from 5,000' to 11,000' in a couple of hours or less...)

 

I just thought of this, could it be the stock 3rd gen. 5.0 fuel filter under the car ? gonna remove it & make a shunt to fill the gap that threads on in its place & drain the old gas at the same time, since its been sittn for over 2 years now

 

A blocked filter/bad gas will not cause it to run rich

Clogged filter will cause a lean condition, and bad gas will make it run like poo. You will be able to smell it

 

yeah i agree it would/ could cuase it to be hard to start & or stall out due to lack of gas though & I also think that its not only a bit redundant but not rated for the press. of the walbro.
I'm thinkin that its stallin out for those reasons(maybe others?) but then theres raw gas left in the system & the next time it starts it backfires a bit too & ifso thats poss. why its smellin so rich aswell? just a guess at this point

 

Lets put the threads together so we dont cover the same info twice

http://www.ls1tech.com/forums/conver...ont-run-2.html

Ok, you need a filter, two wont hurt, but you only need one. The second wont impede flow that much to make any difference unless its the original with 200,000 miles on it. Its unlikely the pressure rating of the filter has any effect on operation. That filter was used in all 3rd gens, CFI, V6, carb, TBI, TPI along with a slew of other GM vehicles of both high and low pressure systems

Im still leaning to a bad tune, but install a ALDL connector and pull the codes. We need to have something to work with

 

cool I'm workin on gettn codes, if any? I'll post 'em up here, in the mean time i gotta finish up my trans pan & other loose elect. ends before i can go any further here.
should be good to go by this w/e

 

Quick question, did you have the PCM tuned for an auto or manual?

 

they were supposed to del. the trans. in order to run my 700r4 that was set up for racing w/ the last motor i had in the car(used to be a 12sec. 1/4mi. car)
now im wonderin what they really did after hearin all the bad publicity about the "wait4meperformance" guys, i heard they were really good before i got mine dun.
figures!

 

When I was wiring up mine i noticed some of the wires were pretty close to a heat source. When I cleaned up the wiring and moved them away the car ran perfectly! Heat causes resistance in the wires which in turn will throw false codes if not properly handled and installed.

 

ok, so i got the trans pan on (hughes deep alum.) & finished up sum of the wiring stuff & its still really hard to start to the point it drains the batt. i hafta crank it 3-5 times before it starts, when it does it revs up to about 1500-1800 rpm then dies, but no more back firing or rich smellin exh. now its runnin smoother before it dies & it acts like this with & w/o the maf. not really any diff.
its like the timing is way off or sumthin should i send the pcu back to wait4meperf. to be put back to stock perameters, or what?

 

wich obdII code reader should i get for "04 gto swap?

 

Any OBDII scanner will do the job

 

ok, I think I found the prob. or one of them? on the "C1" side of the harn. there are two orange wires #'s 19 & 20 my sheet says #19 goeas to "ign. 3 volt" & #20 to B+ so does #19 goto the 3rd gen ign. wire that geos to the coil from the key or to B+ ? right now I have it coming off the key'd ign. wire but I dont see any voltage when I turn the key, is this the prob here?

 

I was also wondering if the fuel pump needs to be "hooked into" the ls1 pcm? i have it running offf the 3rd gen harn. I was told that would work but ...?

 

Not sure about the 4th gen body connectors

The 3rd gen fuel pump relay will run the LS1 pump from the LS1 PCM just fine. Relays dont care what controls them

 

thanx for the info but I already tried that too & yer right the fuel pump runs great regrd. of wich relay powers it, I dont think its a fuel iss. but I dont know what the psi is @ the rails yet.
I was wondering if the ls1 pcm needs to be able to "see" or "control" the fuel pump at all?
I was told that I hafto wire the pump into the ls1 harn. or it wont run (by the guy who sold it to me)

 

The PCM gives 12v to engage the fuel pump relay. The relay takes care of the rest

You can engage it via toggle switch for testing purposes if need be, but if it primes at all (you can hear it clearly) then its doubtful your problem is there

Did you pull the codes yet?

 

HOLY CRAP!!! I freekin fig'd it out & got it running, sounds F'n awesome! so this whole time it was the relay pack that was spliced into the '04 harness to get power to all the things that need it, like the fuel pump for instance & the fan for another.
so all this time ive been fighting bad electronics(relays) it turns out i dont even need the relays that were spliced into the haness at all & the stock 3rd gen fuel relay was shot(i guess) so i replaced it and ran a new batt+ w/ fuse holder to it & BAM! she roars like a tiger!
so the thing to take away from all of this is that not only does the stock 3rd gen. relay work just fine & you dont need abuncha crap added into & hanging off of the harness(like a big *** relay pack) BUT, the LS1 "PCM" needs "see" or "control" (so to speak) the pump in order to keep the motor going correctly or else it doesnt get enough fuel & the motor runs like *** & dies a few seconds after startin.

thanx again to every one for all yer help with this & I will most likely still be around here as I STILL have sum issues to work through yet! & I really kinda like this site!

 

so far it looks like the tune i got from wait4meprf. is gonna be ok afterall, the car seems to be runnin good in the shop but well see how it runs on the street? i'll hafta post sum pix of her on here.
CANT WAIT TO DRIVE THE OLD GIRL AGAIN!!!

 

WTF! now my fuel pump wont run at all unless i "jumper" it, but the motor still wont start even with the pump hot wired & it doesnt look like theres any spark either.
is it poss. i fried the ecm or something?

 

If you have to jumper the relay and it works, then the PCM is not sending the proper signal to engage

PCM damage is possible, but it will throw a code. Did you scan the codes yet?

 

Possible see what codes have set in the system and go from there.

 

too much to read, but did you hook up a scanner to see if there are any codes stored? you did upgrade everything right? the conversion is a complete OBII setup?

 

Then dont post. Good info is just as prevalent in the middle of a thread as the top/bottom

He hasnt reported back in nearly 3 weeks, so either he gave up or the issue was something simple and he figured it out

Since we were focusing on his fuel control circuit which was very simple, chances are good he figured it out