Ls1 running issue - LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums
 
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post #1 of 6 (permalink) Old 09-21-2018, 06:42 PM Thread Starter
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Ls1 running issue

I have a 2000 ws6 m6 235/243 .630 .610 with PRC 225 heads and ls6 intake full exhaust. Having an odd issue where I sorted out the build and car ran good for about a thousand miles (LOL) then had an issue with a bad maf and hp tuners mpvi2 bricking my ecm.


I replaced my ecm and maf and car is still bucking and idling very bad. When cold started the initial start car idles good for about 4 seconds then starts struggling to get idling. When giving throttle it’s very slow to respond and acts very odd. Once warmed up car idles a bit better but when driving at low rpm car intermittently hesitates bad.


Almost like traction control kicking in. At WOT car screams. Noticed at a constant rpm my fuel trims go WAY positive but as soon as a quick touch of gas they calm back down. This is the same tune car was fine with so I don’t think it’s a tuning issue.


Tps is newish but it’s an advance auto brand. I can attach logs for hptuners. Anyone have any suggestions??

Last edited by cocobolo95; 09-21-2018 at 09:03 PM.
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post #2 of 6 (permalink) Old 09-21-2018, 09:05 PM
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Have you put car on an obd 2 scanner that does real time sensor data scans? A lot of useful info can be gleaned from the sensor scan.


And welcome to the forum.
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post #3 of 6 (permalink) Old 09-21-2018, 09:32 PM Thread Starter
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I have hptuners on my laptop and a 9875 actron(I think that’s what it is) which does graphing for pids and things and I honestly have not seen anything at all wrong with it. Throttle actual % is linear.

I think I’ve got the tps voltage at .61 at idle and iac counts around 40-60 The O2s look like they are reading lean at idle even with the fuel trims going up but car smells very rich and as soon as a little throttle blip to push some exhaust past them they shoot up to +.800 mv.

Entire pcv system is new and new felpro intake gaskets on ls6 manifold. New gm map sensor I got off eBay which seems to read right. Car is tuned by Pat G so it shouldn’t be a jacked up tune. I’ve tried to get a hold of him a couple times about looking at these logs but haven’t got a response as of yet.

Car has new iac and iat as well. I honestly have no idea what else it can be. I’ve changed plugs and wires even though plugs were new when I installed the heads. The whole situation is very odd to say the least.

Last edited by cocobolo95; 09-23-2018 at 08:47 AM.
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post #4 of 6 (permalink) Old 09-22-2018, 08:37 AM
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About the only other thing I can think of is an exhaust leak before the o2's, that is pulling in unmetered air. The o2's are seeing lean exhaust because of the air and making a very rich mixture.


I would say look for vacuum leaks, but that would pull the unmetered air into the combustion chamber where it would become part of the mixture. Pcm would add more fuel to mixture, but not as much as you indicate you are getting.
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post #5 of 6 (permalink) Old 09-22-2018, 04:07 PM Thread Starter
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I have absolutely no clue why it’s acting stupid. In the upcoming week I’ll take it to the shop and put it on a lift to get a look at the exhaust. I want to think it’s something to do with fuel mixture more than a vac leak as my map sensor showing I have decent vacuum.

And I’ve eliminated the rubber T behind the intake and just have the AC vac line going into it since my emissions and all that is deleted so I don’t have many spots a vac leak can occur.

I believe it’s some kind of sensor just because both short terms climb up to the 15s-20s. It’s beyond frustrating to the point I’m here looking for ideas

Last edited by cocobolo95; 09-23-2018 at 08:49 AM.
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post #6 of 6 (permalink) Old 09-24-2018, 10:35 PM Thread Starter
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I may have found my problem after I put my new map in and compared my old logs. My map at idle on my old map was about 68 Kpa and with my new map I’m readin around 30. Is there a single table in hptuners that I can skew back?
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