Fresh build starting and idle problems
Thread Starter
Teching In
Joined: Mar 2014
Posts: 8
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Fresh build starting and idle problems I have been reading through this entire forum trying to find info to use and i have found a lot of good stuff but nothing that seams to be close enough to my problem for me to be sure I'm not chasing a ghost.
2001 Pontiac Trans am WS6 auto 4L60e Still has stock LS6 intake manifold, MAF, throttle body, and fuel rail. Air injection system deleted, rear O2s deleted, VATS deleted, tuned by mail order tuner (referred by TSP).
Mods: PRC 227 heads w/ 58cc chambers, PAC .660” dual spring kit, titanium retainers, 2.065” dia hollow stem intake valves, 1.600” dia hallow stem exhaust valves, OEM rockers w/ TSP trunnion upgrade, TSP 233/239 .600/.600 112 LSA cam, forged TSP 3.622” stroke crank, TSP forged H-beam 6.125” rods, CP forged flat top pistons (3.905” dia, 1.305” ch, -2.7cc flycut), .230” wall wrist pins, Melling high volume oil pump, Cometic .040” head gaskets, Morel link bar roller lifters, Manley 7.425” 5/16” dia pushrods, TCI flexplate, RPM speed single roller HD timing set, SacCity billet barbell, PATC level 3 4L60e build kit #803, Yank ss 3600 stall converter, Racetronix 255 LPH fuel pump w/ hot wire relay kit, FIC 36# injectors, TSP 1 3/4” headers, TSP off road Y-pipe, Borla 3” adjustable cat back, SLP air lid, UMI strut tower brace, UMI subframe connectors, UMI non-adjustable panhard rod and LCA’s, UMI tunnel brace w/ safety loop. Should have close to 11.4:1compression ratio.
I just finished building this engine a few weeks ago. As part of this i replaced every sensor on the engine and intake except for the MAF and O2’s, even replaced the IAC. I sent the pcm out to be tuned while i was putting the engine, k-member, and transmission back into the car. I get the pcm back, plug it in, start the car and it ran for a minute or two and died. Tuner tells me to adjust the throttle body set screw. I open the throttle up 1 full turn and that fixes the idle issue but the car throws a P0118 code (coolant temp circuit high voltage). I replaced the coolant sensor, cleared the code, and it has not returned so that problem is fixed. So after i replaced the coolant sensor i cranked the car, let it warm up to operating temp, checked the transmission fluid level and added some fluid to get it i to the proper range. Then i got in the car, shifted it into drive, and the car stumbled a bit but caught its self and idled back up to normal so i pulled out of my driveway to take it on a test drive in my neighborhood. First i did a slow acceleration up to about 20 mph and it did fine, so when i turned onto the next road i tried a normal acceleration to 35 mph but the car fell on its face and did not want to accelerate. So i let off the gas and the car almost died but i managed to limp it back home and as soon as the car came to a complete stop, it died and i could not get it started again and it was throwing the P0135 (bank 1 sensor 1 O2 heater circuit). The next morning i checked the static fuel pressure. I have 62 psi while the pump is running and it holds 50 after it shuts off. When i started the engine, my fuel pressure bounced between 60-65 psi but it only ran for a minute then shut off. After i let it sit for a while, i got it started again just long enough to drip water on the headers trying to see if i have a dead cylinder. I don't think i have a completely dead cylinder but judging from the water test, i think the #5 & #7 cylinders exhaust is a lot cooler than the others and it smells like its running rich. Anytime i rev the engine now with the car in park, it revs fine but when i let off, the rpms drop so low it dies. So i plan on replacing the O2 sensor just so i know there is a good one in there and hope it fixes the rich mixture problem, but i’m also going to pull the plugs and see what they look like and if it all looks good i plan on making sure the coils are getting the proper voltage from the pcm. Is there any way to check the coil packs other than swapping them around? And if all else fails, should i try a compression check? Could a bad O2 heater cause it to run overly rich enough to kill the engine? I need ideas on what to check so that i know i have covered all my bases before i blame it on the tune.
Side note, don't have hp tuners or anything like that. I only have a scanner that will pull the codes and clear them. Thanks in advance.
2001 Pontiac Trans am WS6 auto 4L60e Still has stock LS6 intake manifold, MAF, throttle body, and fuel rail. Air injection system deleted, rear O2s deleted, VATS deleted, tuned by mail order tuner (referred by TSP).
Mods: PRC 227 heads w/ 58cc chambers, PAC .660” dual spring kit, titanium retainers, 2.065” dia hollow stem intake valves, 1.600” dia hallow stem exhaust valves, OEM rockers w/ TSP trunnion upgrade, TSP 233/239 .600/.600 112 LSA cam, forged TSP 3.622” stroke crank, TSP forged H-beam 6.125” rods, CP forged flat top pistons (3.905” dia, 1.305” ch, -2.7cc flycut), .230” wall wrist pins, Melling high volume oil pump, Cometic .040” head gaskets, Morel link bar roller lifters, Manley 7.425” 5/16” dia pushrods, TCI flexplate, RPM speed single roller HD timing set, SacCity billet barbell, PATC level 3 4L60e build kit #803, Yank ss 3600 stall converter, Racetronix 255 LPH fuel pump w/ hot wire relay kit, FIC 36# injectors, TSP 1 3/4” headers, TSP off road Y-pipe, Borla 3” adjustable cat back, SLP air lid, UMI strut tower brace, UMI subframe connectors, UMI non-adjustable panhard rod and LCA’s, UMI tunnel brace w/ safety loop. Should have close to 11.4:1compression ratio.
I just finished building this engine a few weeks ago. As part of this i replaced every sensor on the engine and intake except for the MAF and O2’s, even replaced the IAC. I sent the pcm out to be tuned while i was putting the engine, k-member, and transmission back into the car. I get the pcm back, plug it in, start the car and it ran for a minute or two and died. Tuner tells me to adjust the throttle body set screw. I open the throttle up 1 full turn and that fixes the idle issue but the car throws a P0118 code (coolant temp circuit high voltage). I replaced the coolant sensor, cleared the code, and it has not returned so that problem is fixed. So after i replaced the coolant sensor i cranked the car, let it warm up to operating temp, checked the transmission fluid level and added some fluid to get it i to the proper range. Then i got in the car, shifted it into drive, and the car stumbled a bit but caught its self and idled back up to normal so i pulled out of my driveway to take it on a test drive in my neighborhood. First i did a slow acceleration up to about 20 mph and it did fine, so when i turned onto the next road i tried a normal acceleration to 35 mph but the car fell on its face and did not want to accelerate. So i let off the gas and the car almost died but i managed to limp it back home and as soon as the car came to a complete stop, it died and i could not get it started again and it was throwing the P0135 (bank 1 sensor 1 O2 heater circuit). The next morning i checked the static fuel pressure. I have 62 psi while the pump is running and it holds 50 after it shuts off. When i started the engine, my fuel pressure bounced between 60-65 psi but it only ran for a minute then shut off. After i let it sit for a while, i got it started again just long enough to drip water on the headers trying to see if i have a dead cylinder. I don't think i have a completely dead cylinder but judging from the water test, i think the #5 & #7 cylinders exhaust is a lot cooler than the others and it smells like its running rich. Anytime i rev the engine now with the car in park, it revs fine but when i let off, the rpms drop so low it dies. So i plan on replacing the O2 sensor just so i know there is a good one in there and hope it fixes the rich mixture problem, but i’m also going to pull the plugs and see what they look like and if it all looks good i plan on making sure the coils are getting the proper voltage from the pcm. Is there any way to check the coil packs other than swapping them around? And if all else fails, should i try a compression check? Could a bad O2 heater cause it to run overly rich enough to kill the engine? I need ideas on what to check so that i know i have covered all my bases before i blame it on the tune.
Side note, don't have hp tuners or anything like that. I only have a scanner that will pull the codes and clear them. Thanks in advance.
TECH Fanatic
Joined: Oct 2014
Posts: 1,220
Likes: 179
From: Virginia
Yes, running too rich at idle speeds can foul your plugs out quick. So yes, a bad heater circuit could potentially cause this, as with heated O2's, they have to reach a certain temperature to be accurate. It sounds like it just needs a tune, honestly. I've never done the mail order thing, so I can't speak to experience, but I would say it definitely will not be as accurate as a street or dyno tune can be due to lack of real time data. This doesn't mean that the tuner messed up, it's just hard to do over a telephone or the internet. Idle happens to be one of those things that is very hard to nail down perfectly when the engine has changed significantly over stock fueling/airflow requirements, even sitting in the car with a scanner lol. Compression has a massive effect on this.
Yes definitely check the plugs. They are probably fouling out from over fueling.
Yes definitely check the plugs. They are probably fouling out from over fueling.
Thread Starter
Teching In
Joined: Mar 2014
Posts: 8
Likes: 0
Thank you for the response. I will change the O2 and check the plugs when i get a chance. Its starting to look like hptuners might be a good future investment for me since dyno tunes are not an option for me in the area i live in. My goal with the mail order tune was to get it running well enough to make the 3-4 hour drive to one of the nearest shops with a dyno.
Staging Lane
Joined: Feb 2017
Posts: 85
Likes: 9
From: Hamilton Ohio
Jason, I have a very similar problem with my new 5.3 LS build. I am waiting for a new TPS in the mail, to attempt to fix my rev then stall issue. I may need to adjust my TB screw but I wanted to put a new TPS on first just to be sure its not bad, I have no idea how old it is.
Just out of curiosity how far out is your TB idle set screw? Does it crack open the butterfly at all? how far does the set screw stick through the TB housing thus opening the butterfly?
Here is a link to my thread, see the youtube video for how it is running.
https://ls1tech.com/forums/pcm-diagn...rt-issues.html
Just out of curiosity how far out is your TB idle set screw? Does it crack open the butterfly at all? how far does the set screw stick through the TB housing thus opening the butterfly?
Here is a link to my thread, see the youtube video for how it is running.
https://ls1tech.com/forums/pcm-diagn...rt-issues.html
W/o data log[s], tune posting, it's all pure speculation.
Throwing parts at it, won't get the job done.
The idea of a new TPS to cure the issue may only lighten your wallet. Tune settings may address the problem[s].
Throwing parts at it, won't get the job done.
The idea of a new TPS to cure the issue may only lighten your wallet. Tune settings may address the problem[s].
Thread Starter
Teching In
Joined: Mar 2014
Posts: 8
Likes: 0
Jason, I have a very similar problem with my new 5.3 LS build. I am waiting for a new TPS in the mail, to attempt to fix my rev then stall issue. I may need to adjust my TB screw but I wanted to put a new TPS on first just to be sure its not bad, I have no idea how old it is.
Just out of curiosity how far out is your TB idle set screw? Does it crack open the butterfly at all? how far does the set screw stick through the TB housing thus opening the butterfly?
Here is a link to my thread, see the youtube video for how it is running.
https://ls1tech.com/forums/pcm-diagn...rt-issues.html
Just out of curiosity how far out is your TB idle set screw? Does it crack open the butterfly at all? how far does the set screw stick through the TB housing thus opening the butterfly?
Here is a link to my thread, see the youtube video for how it is running.
https://ls1tech.com/forums/pcm-diagn...rt-issues.html
Staging Lane
Joined: Feb 2017
Posts: 85
Likes: 9
From: Hamilton Ohio
I cant tell you the exact measurements but i had it set one turn further in than the stock setting. The car is currently at the local performance shop right now and they are still having problems getting it to idle at all. They have tried multiple tunes. They have even tried a speed density tune and still no dice. This is really getting frustrating. They said they want to play more with the fuel and airflow data but if that doesn't work, they mentioned wanting to check the mechanical side like timing. But the fact that i was able to get it to run and take it on a short drive before it died, i wouldn't think it would be mechanical. I’m honestly considering just paying for hptuners and learning how to do it my self. This is my second round with tuners and its not going well.
Good luck with your situation, I'm sure it will get sorted eventually.
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Staging Lane
Joined: Feb 2017
Posts: 85
Likes: 9
From: Hamilton Ohio
One bit of advice I can offer is to check your fuel trims. You can use the Torque app and a Bluetooth OBD2 reader, they are cheap on Ebay. Then set it up to read a selection of data including long and short term fuel trims. These will help you identify what to go after. There are lots of good fuel trim videos on youtube that will help you understand what they mean.
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Thread Starter
Teching In
Joined: Mar 2014
Posts: 8
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Well, i asked the local shop to do a compression check. They found the #7 cylinder is dead. They say a valve is hung open. I checked piston to valve clearance while i was putting the engine together and it all checked out good. And yes i used a solid lifter to check. Is there anything else besides a piston slapping a valve that could cause this? I really don't want to pull the head off but it looks like that is whats going to happen.
Thread Starter
Teching In
Joined: Mar 2014
Posts: 8
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Problem solved! Originally, the pushrods i installed were just a little too short and made an annoying ticking sound so i put .025” longer pushrods in. When i put the pushrods in, i missed the lifter with the pushrod on the #7 exhaust valve. It was sitting on the lifter’s link bar and hanging the valve open. Luckily, the piston is flycut enough that it never touched the valve and the pushrod did not get bent. I dodged a big bullet on that one. We put the pushrod back in correctly this time and compression check was good and it fired right up. I just want to thank everyone who chimed in and say that I'm sorry for waisting your time because of a stupid mistake on my part.