Ls-1 guru`s = HELP ME

[jrhall]

I run an 02 Ls-1 in my jeep with howe Harness/comp. After a trip of to witc 2 weeks ago, my motor has developed a miss.
It misses at idle and when i hit the rpms. Ive replaced plugs, injectors, filter,and fuel pump and checked each coil pack.
Found that the filter had came apart and trashed my fuel pump.
Fuel pump at idle was 47lbs of pressure and when i blipped the throttle would dip down near 40 lbs. So i warranted the pump and put it on this evening, but still nothin.

All parts have been replaced and still the miss is there... Any more suggestions?

 

[BamaTJ]

Every LS motor I have seen start running like piss has been because of the MAF sensor. If you have a buddy with a vortec or other motor that share the same MAF, swap it over and see. If it performing poor and not hitting the limiter, I would definately say that is it

 

[Cole]

Every LS motor I have seen start running like piss has been because of the MAF sensor. If you have a buddy with a vortec or other motor that share the same MAF, swap it over and see. If it performing poor and not hitting the limiter, I would definately say that is it

x2, thats what marks was doing in Harlan and Donalds cab truck at King of the Hill.

 

[draggbody]

can you trace it to a particular cylinder??? what does the code read, a particular cylinder or random multiple misfire, if it a specific cylinder then i bet against a MAF and would think there is a mechanical engine problem, let us know, and we can narrow it from there...

 

[Marty]

You def should have more fuel pressure at idle for one, which should have anything to do with the MAF sensor. Check the regulator as well, I assume you run the stock one, and they are less than 50 bucks at the parts store. You can try cleaning the MAF with the cleaner they sell at NAPA. Anyway you can borrow a scan tool? that would help narrow down the problem.

 

[lobie]

The fuel pressure should be around 58 psi http://www.ls1tech.com/forums/fueling-injection/965728-what-stock-ls1-fuel-pressure.html
Also check on the back side of the heads and make sure the grounds are bolted tight against the head.

 

[jrhall]

random missing. . Hooked it up to a fancy scanner the other night but never threw any codes... It seems to be a random miss for what we can tell.

Does the fact that i unhook the 0`2s sensors while the jeep is running and nothing changes mean anything?

 

[draggbody]

no the o2s wont change anything that you will notice while its running... so it consistantly misses, like if you crank it up, it skips... thats not random... when i mentioned random, it means that it is impossible to narrow it down to one cylinder... so does it do it all the time, or sometimes it will and sometimes it wont....

 

[jrhall]

my bad, it misses the entire time that it is running. ive tried pullin a plug wire off and didnt seem to change the idle and it still missed. Once it warms up today,, ima try to tinker some more with it. Ima try to get video if that will help.

 

[Toddy]

I would bet the fuel reg. If it got enougth trash in the pump to mess it up it got past it also. Sounds like a lack of fuel is what is making it miss.

Toddy

 

[mw87toy]

Have you pulled the injectors and checked them?

 

[Marty]

Have you pulled the injectors and checked them?

reading comprehension 1st post He replaced the injectors.

 

[YOUNG]

LS1's and all the LSX family of engines need at least 60 PSI of fuel pressure at an idle or WOT. Spend the money and get a good pump(Holley, Walbro etc.).

 

[GStone]

I ran mine at 52psi for years, no problems. Check you MAF and I didn't see if you changed the wires, did you?

 

[jrhall]

replaced the map sensor and mass air flow... still no luck. I have got to check fuel pressure since new pump was installed. Im runnin an e8284 fp. ima check the fuel regluator when i go back to work on it....

 

[GStone]

I didn't see if you changed the wires, did you?

 

[jrhall]

plug wires? ??? i havnt changed any wires yet, all sensors and misc pumps, filters...ect

 

[Blase]

If the plugs and plug wires don't work check out the fit on your #7 injector. I had to change my intake becuase the fit was too loose and it was sucking in air and dirt. It's a long shot but a shot no the less. I was told afte :flipper:r I found the problem that this is common on certain LS series intakes.

 

[jrhall]

i noticed on my motor that one of the plug wires has no slack(as in its tight from plug to coil pak) but its been on there for 2 years and it is still giving plenty of spark.... it lit my ass up the other night clean off the trailor as well as 4 others. we are goin to do a compression test soon to check for an oops inside the motor.

 

[draggbody]

if it shocked you then the current is flowing on the outside of the wire... put some plug wires on it and i'll bet that will take care of it...