someone had mentioned it might be one of my coils and said basically just start the car to temp and unplug one of the coil packs to see if it does the same **** with it off the car...well i took off the #1 and the cars personality didnt change one bit...didnt feel like it was firing on just the 7 cylinders even though i know only 7 were actually getting spark? Should i go ahead and replace just that one coil or is there more to it? It was just straitup wierd IMO that the car didnt run any rougher than normal...for me to test out the other 7 is a major pita with the air and egr being in the way of pretty much every wire but i knew i could do #1. So what is everyones thoughts on this now...please?

Thanks
Bill

 

Replace the #1 coil. If the car didn't idle any different, then it could be a open coil. If that's the case then you've been running 7 cylinders. I'd put an ohm meter across the ground pin & the spark plug wire connection point on the coil with the wire off of course. If the coil is open then you will have an open (High resistance reading). If the coil is good it should read ohm's of some sort and see a meter deflection. I'll go out right now & read my number one coil with my ohm meter & post back in a few minutes, Fred

 

I couldn't get an ohm reading on my coil.. Anyways, pull the spark plug & see if it is burning right, wet with gas etc. Also check the plug wire with your ohm meter and compare it to a couple others for a comparison.

I'd think that if you removed wire & it didn't run any different then something is up. What does the spark plug look like? If it's ash white then maybe the injector is bad. Alot of things could cause this sort of thing.

How about pulling the spark plug push it into the wire boot & hold it off the block an 1/2 inch or so & turn the car over, do you see a spark?

Let me know, Fred

 

I'll see if i get spark off the coil tomorrow today i just saw a random spark from the coil to the block every 5 seconds or so so i dunno how to take that...gets more interesting by the day

 

TTT anyone else?

 

Did you check the coil pack wiring harness going to #1?

Like I said before, try swapping coil packs around and see if the misfire jumps to the cylinder you swapped the #1 coil pack to. If it does it's the coil, if not then it could be the wiring harness.

 

From your discreption I am quessing that the engine is running ruff like a missing cylinder and U disabled #1 cylinder since it was the easiest to remove. I am also guessing that the is a new problem and you have had the PCM tuned for that big stick U R running. First I would ck for a vacuum leak. A vacuum leak can disquise itself as a bad cylinder by making the cylinders show little change in RPM when disabled. If none found then I would locate the cylinder that is missing. With OBDII it should set a SES light with either a random misfire code or a specific cylinder miss fire. Another thing that can cause a random miss fire is an erratic crank signal, bad knock sensor, bad MAF and such. Using a Modis or Gensis or something similiar can help figure out what is going on.

 

al 8 cylinders show multiple current missfires via autotap & the P0300 code has been diabled so it wont throw a code, yes i have been tuned, the car doesnt run rough persay just a slight off idle hesiation.

 

I think it is something in the tuning, have you talked to Cartek about it? What do they think it is? Have they driven/ridden in the car when it is doing it?

 

they had one of the newer guys just go out with me to test for missfires w/ tech2 since their initial diagnosis was bad plug wires (msd's) so they found a bunch of missfires so that was their conclusion...but i swapped out wires & that didnt fix the problem nor make it worse so i dont think thats it...i was sick on monday & was at a local meet yesterday so havent had the time to contact them other than emailing the tuner who has yet to respond. Im gonna give them a call today with the "progress" and see what they have to say.

 

Have you tried what I suggested. I'm guessing not.

An aftermarket cam, especially one with as much duration as yours, is going to give random misfires on all cylinders. That's a given. But your main complaint is the #1 cylinder. You said you're not getting a good spark from the #1 coil pack. To rule out that coil swap it with the one right next to it. If when you Atap the car again the misfire jumped over to that cylinder then the coil needs replacing. If not check the coil pack wiring harness. It is easily unplugged from the main harness. From the symptoms you're describing I would tend to believe that the problem is in the wiring harness or connector pins for the #1 cylinder. Since you haven't mentioned any other codes being thrown and the misfire code is disabled it stands to reason that it's an isolated problem with the #1 cylinder. You also said that the plugs looked fine, thus oil fouling does not seem to be the problem. Although the plug may look fine I would replace it with a new one anyway on the #1 cylinder.

Not all misifires work the same way. Some will be noticible at idle and when driving. Some only when driving. While some only at idle.

I don't see how this is tuning related. Can it possibly be, maybe but I would rule out all the ignition components on the #1 cylinder before I made that judgement. Spark plug, coil pack, harness.

If all the ignition components check out and the tuning is good then there are other things that might be causing this particular misfire. The #1 injector could be bad. Incorrectly ground #1 cam lobes. Someone else had a problem with a 231/237 cam. Etc.

Rule out the simple stuff first. Spark plug, coil pack and wiring harness.

 

long live the opti...

 

some of the stuff suggested i have done & some i either havent gotten around to. When i unplug the wire the missfires via autotap jump so i dont think its a bad coil at this point...im thinkin probably the cam has enough lope & ***** that it just disguises the fact its down a cylinder at that point to an extent. Ive asked around to a few people with autotap & this perticular cam if they have missfires on each cylinder and ive only gotten one response back saying they dont so at this point i dont know if i should or shouldnt be getting to see missfires on the cylinders. Let me make something clear...I DONT THINK ITS JUST ONE CYLINDER it just so happens that i only tested one cylinder since with air in my way its not feasible to check the other ones in the same fashion. If i could get a concesus that yah ill still see multiple missfires even with tuning then I'd know its in the tuning otherwise im not gonna start pointing fingers at anyone. I see approx. the same amount of missfires on each cylinders fwiw via autotap...so either my 8 coilpacks have all gone at once...my second set of ignition wires is bad as well as the first...my 8 new ngk55 plugs are bad...my wiring harness has somehow failed on both sides...or this is normal to see the missfires with a cam my size and look somewhere else basically. lol I appriciate everyones help I think ive confused the **** out of some of you though with this post and im sorry. Thanks for your help

Bill

 

 

I would swap the coils, even take a coil from another car, it takes 5 minute and it's easy.

If #1 still misfires bad I would see if the #1 harness has a break in it. Silversurfer is giving you good advice.

 

if i was only having missfires or having some unusually high amount compared to the other cylinders on #1 i would be great advice but in this case https://ls1tech.com/forums/attachmen...achmentid=8085 look at the missfires...they arent condensed to one cylinder.

 

Yeah but.. You said when you took the #1 wire off it didn't run noticeably different.. That IS NOT NORMAL Tim, Fred

 

From reading through some of your other posts about the problem you're having I got the impression that although you're getting misfires on all 8 cylinders, on a couple of them the condition is more chronic. If that's not the case, then maybe the problem lies elsewhere. It could then possibly be that they didn't street tune the car as you said.

I don't think it's the fuel pump because if it was crapping out you'd be going really lean at WOT. But if somehow the fuel pressure regulator went bad the car might be getting too much fuel at idle and part throttle. Not a problem at WOT because the rich mixture could have been turned down, by lowering injector pulse width, at Cartek when it was tuned. Hook a fuel pressure gauge to the motor and see what's up.

Did you notice the stumble at part throttle when you first drove the car after it was tuned? If the problem wasn't there at first then try reseting the PCM/ECM by unplugging the big 50 amp fuse and the small 10 amp fuse in the 2 fuse blocks. After letting the car sit for a while plug them back in and re-Atap the car. If it's a sensor problem it might not come into effect right away. When I do this to my car the problem I'm having with the 3.96* of knock does not manifest itself for about an hour's worth of driving and I get normal timing. But then the computer learns and it goes back to limp home mode and 15* of timing. Easy to do and worth a try.

You said once you go WOT it takes a couple of seconds before the car starts to boogey. Are you able to power brake the car? Maybe the converter went bad or there's a problem in the tranny and it's locking up the converter at part throttle.

Make a list for us of the things you've done so far to try and troubleshoot the problem. Might shed some light for us.

 

If the misfires are equally high on all cylinders also try borrowing a MAF T and leaning out the base idle, if the car is very rich at idle the plugs will load up.

 

I know this isn't an LS1 but hear me out. '99 'burban 5.7 Vortec. Uses a cam sensor in the distr for it's cam seq. Another shop did a reseal on the intake and just stabbed the distr. back in. Of course it set a code for cam not in seq with the crank. Stick it back in and test drive, everybodies happy. Comes back 4 days later with ck eng lite on, Random misfire especially # seven. At an idle it felt fine yet I could see on the Modis that seven would miss. Get it to hyway speed and you could feel it breaking up. I suspected wires but they looked new, LSS..... the cam sensor was still off like 10* . These engines don't have a timing mark so I am guessing at the exact.

So.... check cam and crank sensors. Look @ STTrim you want it around 128 + - maybe 8 numbers max. Check LTTrim within 10 numbers. Ck cross counts on the O2 sensors, we want the O2's to be switching rich/lean rapidly..... like .2 to .8 and back and forth. What we are looking for is a lean condition to explain the hesitation or even if it is a lean condition. Have we looked for a vacuum leak? If you can, get some carb cleaner and spray along any vacuum hose, fitting, intake surface, anywhere vacuum can leak. Careful around the plug wires, you might find a bad one and let all the smoke out of it.