steiger99

Hey everyone. I'm in the weeds bad and need a miracle. I would first like to apologize for the novel I about to write. I have been to 5 performace shops here in southeastern Michigan and all 5 shops returned the car to me and said they could not figure it out. (This includes livernois motorsports which I was told were a very 'smart' shop that could fix anything....ERRRR wrong)

Straight to the point.

CAR DETAILS:

1995 camaro LT1....now a 383 LT1 stroker, 12.5:1 compression (checks out very good), estimated to be 500 h.p. + by golenengineservice.com. Lloyd Elliot stage 3 heads and cam, pacesetter long tubes, no cats, SLP loudmouth cat-back, 30lb injectors, msd opti, msd 8.5mm wires, autolite plugs, msd coil, stock MAF, PCM tuned 3 times by pcmforless (Bryan Herter), LT4 intake manifold, new walbro 255 fuel pump (pressure is strong and check out to be holding perfectly), cold air intake, egr removed (block off plates could be bad seal??), AIR pump deleted, (I think thats enough background) (THhis motor just dropped recently in btw.

Started right up, broke in the cam, maybe has a total of 40 hours total run/idle time on the motor since it was new.

PROBLEM1: (Dies when motor gets hot)

For a while the car would start and hold an idle with no problem. Now its a tough time to get it to start (20-25 turns before it finally starts, have to gas it to get it to hold an idle.) Once its started it would hold an idle and rev while the motor was still cold. As soon as the car get warm, big trouble happens. It starts bogging down, slow response when giving it gas, misfires throughout any motor rev, eventuially when it gets too hot under the hood it will simply die. Starting it after it dies is simply not an option. What would be a list of reasons as to why it would run horrible once it reaches operating temp.

1. bad coil?
2. bad ICM?
3. Bad coil wire?
4. Bad opti? (Or would the opti make it bad regardless of temp?)
5. BAD o2 SENSORS? How do you know if the o2's are bad? What happens?
6. bad spark plug wires?
7. Wrong gap on the spark plugs? (12.5:1 compression blows my spark out so I have it set at .030-.035 (I think stock calls for .040-.045??)


When I installed the brand new msd opti was I supposed to mark the position of the crank or was it ok to just line up the little key-hole on the optispark with the dowel that stick out of the motor by the crank???? What if that dowel is sticking out too far, would that destroy my opti immediately? How far out should that dowel pin be (Anyone have a link to a picture of a dowel properly sticking out that I could see?) I did not mark the crank and its quite possible I rotated the crank to install the new opti. I did line up the dowel on the motor to the opti corectly and it fit nicely but if there is something else I needed to do or check, I might have failed installing the opti correctly.

Also I was getting a major misfire/backfiring right at 4000-4200 rpm's consistently when accelerating soft or hard in any gear. At any rpm lower than that, the car would run very good and hardly could notice any hesitation but as soon as I hit 4000 rpms (BOOM, POP, BANG, Smoke out the exhaust, car didn't stall, just had to catch it and anything under 4000 rpm's the car would run, shift and drive like nothing was wrong. What could this be:

1. Vacuum leak? (Bad egr block-off plate sealed?
2. opti?
3. weak spark?
4. weak fuel pressure? (it was weak/leaking pressure but that is now fixed, however the car hardly starts right now and I have to gas it all the time just to keep it running.

I checked all my grounds, checked the compression, checked the new fuel pump and pressure is holding strong (44 psi), I have another new MSD opti showing up this week, new msd coil, (stock 90,000 mile ICM , what would a bad ICM symptoms be?), new plugs, new wires, new 02 sensors literally going in tomorrow night.

Oh, can you tell me what this mean.... I have MSD coild p/n 8226. I had it tested and this is the results: primary=2.46, secondary=8.54. What do these specs tell me? I can't find a chart to let me know if these numbers are good or out of spec. Can anyone let me know if these numbers are good or bad? This is a new coil (10 hours of use).

Last thing is I just noticed and I'm done, I promise. I just found out my lower left vacuum tube that connects to the lower left back of my 58mm BBK throttle body was missing the vacuum hose that connects to my purge canister (Apparently I lost that stock hose that goes to the purge canister and was driving around with these both wide open. Could that be the vacuum leak that was causing the misfire at higher rpms? I noticed if I plugged the hole on the throttle body with my finger while the car was running it would run so much smoother and when I released my finger it would run a lot rougher. I did buy a new vacuum hose to connect the throttle body to this 'purge canister' thing so hopefully that would be one of hte many problems causing me al the issues.

If you have any advice, suggestions, want to come over and I will PAY you to help me trouble shoot it, let you drive it for a week if you are able to pin point the problem and get it running , pretty much anything you can give me would be so appreciated. I have lost all hope and after I put all these new parts on, I am out of ideas.

Thank you so much for reading my auto-biography, again I apologize for the length, I'm just desperate and have been tirned down by 5 performace shops so you guys are my last hope.

Sincerely... Joel
248-462-0619
steiger99@hotmail.com
Brighton, mi 48116

reamo04

do you have any way to datalog it?

Injuneer

Yes, a missing vacuum hose from the EVAP purge solenoid to the throttle body creates a vacuum leak.

As long as you got the dowel pin in the correct hole, its installed correctly. With the vented Opti if the pin is in the wrong hole, it isn't going to run.

Shoebox has info on the dowel pin length:

http://shbox.com/ci/cam_install.html

Shoebox also has an idea to keep the IC Module cooler:

http://shbox.com/1/4th_gen_tech2.html#ICM_cooling

Appears you bolted an LT4 intake (OEM??) to LT1 heads. If its a GM LT4 intake, was the intake machined to allow it to bolt properly to the LT1 heads? If you don't do some cutting, the top of the LT4 intake runners interfere with the valve cover rail on the LT1 heads.

Have you scanned it for codes?

Have you measured the fuel pressure on the road, under heavy throttle/high RPM?

97SS0594

i was just gonna mention the LT4 intake, the ports dont line up with lt1 heads.

RamAir95TA

If Golen built it, no wonder it runs like crap.

/rant

<Puck>

If it idles fine until it warms up I would think its the ICM or O2s.

An exhaust leak before the O2s could also be giving them a bad reading. Did you use the paper garbage that pacesetters come with?

Injuneer

The LT4 manifold ports do line up with the LT1 head ports. While the LT4 heads have 0.10" taller ports than the LT1, the LT4 intake ports are virtually identical to the LT1 intake ports. There is just more metal at the top of the LT4 runners to allow them to be ported to match the LT4 head ports - but out of the factory, there is a mismatch LT4 intake to LT4 heads. Its this excess metal that hits the valve cover rail on the LT1 heads. Appears GM ran out of development money on the LT4 project, and never finished the intake manifold revisions.

blackFbird_98

ok I am retarted and cant think maybe someone can help me out.. I had to adjust the sensor (dont remember the exact name of it) on the passenger side of the TB.. if memory serves me correct you have to drill a slot in it untill it reads .3-.5 mv at idle.. when I did mine it helped with the idle..

94zgreenmachine

TPS? Throttle position sensor

hsyr

I doubt this is your problem but I could see it being one. Isn't 30lb injectors too small for your setup? I would think you would need either 36lb or 42lb in there. Anyone else agree?

steiger99

Thank you guys very much for spending time to help me troubleshoot my dream project turned nightmare.

To answer most comments here goes:

1. The plug wires were FOR sure connected to the correct location (quadruple checked many times)

2. The intake manifold I have is definitely an LT4 intake manifold. Llyod Elliot ported my stock LT1 heads and I was told the LT4 intake manifold was a good upgrade and that is the only reason why I traded my ported LT1 manifold for it. Should I go back to the ported LT1 intake manifold? Is the LT4 intake manifold a potential source of my current problem?

3. Autozone checked my coil, its for sure bad. The dam thing must have been bad out of the package because it literally has less than 1 hour of use and is already bad, whats up with that. I have a new coil and it is going on

4. MSD is rebuilding my opti/fixing it so I know it is working perfectly. I should have it by next week. I did this because out of the 5 shops I took my car to, all 5 said it was the opti and they wanted 1000 bucks to fix it. I told them I have done the opti 3 times and would not be paying them thank kind of money for a job I am able to completely finish is less than 4 hours total.

5. I just put a fuel pressure gauge on the schrader valve and left it sit overnight, its holding strong at 43psi right now after 12 hours.

6. The TPS sensor is the post that really caught my attention. I remember drilling it out so it could swivel but I never checked the voltage so this is something I am going to need a little more direction on. How do I check the voltage of the TPS? I'm guessing I loosen both bolts while the volt meter is hooked up and the key is forward, then once I see the right voltage I tighten the screws? What is correct voltage? Do you know of a tutorial or guide/sticky posted somewhere I could read the instructions on how to properly set the TPS voltage?

7. The gounds are for sure all cleaned and tight.

8. I have brand new o2's and they are going on when the opti shows up along with the new coil.

9. I have an adjustable fuel pressure regulator, right now I have it screwed as tight as I can get it and it is giving me 50psi while the pump primes and then drops me down to 43-44 psi with the key forward in the on position. Is this a good psi rating for 30lb injectors and a 255 walbro pump?

10. The TB vacuum leak I did find and when I did I put my finger over the hole and it was like the car ran smoother than it did when the motor was stock. We put a temporary cap over the spot on the throttle body where the hose was missing and the car would rev so nice and crispy. Quick throttle response, smooth and no apparent misfiring on revs under 3000 rpms. I didn't go higher than 3000 rpms because the car was still cold and we just started it. I let it run with the vacuum leak capped and as soon as the fans kicked on and the car hit operating temp, my buddy gave it a little gas and it backfired, smoke came out from the intake manifold and air filter some how and the car would not start for hte rest of the night. The next day I was able to get it to start but it took a good 30-40 turns and lots of pedal pumping (even though its fuel injected) to get it to start. When it started, it ran really really rough so I just shut it off that is when I decided I need your help to troubleshoot this.

SO I have a new fuel pump, new fuel filter(s), new opti, new o2 sensors, new coil, almost new plug wires, almost new plugs, (14 year old ICM still), 110 octane gas, new waterpump, and new coolant.

What else could be the source of the car getting hot and just not running? Would the TPS not being set correctly be the source of my probelm? What setting am I looking for on the TPS? Would the TPS affect me at higher rpms and be giving me the huge misfire or just at idle?

Should I get a GM ICM since odds are I will still run into my car stalling once it gets hot? Or do you think I have invested in enough potential fixes for now and should fire it up and see where I stand? What is

Hal Fisher

From everything I've ever read about running bad only when hot it's the ICM.

Hal

94zgreenmachine

Bad info on the intake. It is the LT4 heads that would make the difference with the intake AFTER the intake is ported to match the raised runner on the LT4 head.. The ports on the LT4 manifold are the same as the LT1. Did Lloyd tell you that?
This isn't the source of your problems though. You got duped.

Injuneer

2. Nothing wrong with the LT4 intake, and no benefit from the LT4 intake. But if is was not machined to eliminate the interference with the valve cover rail, it may not allow the intake to seal correctly to the head.

5. What is the fuel pressure out on the road, under max power/RPM. All you have proven right now is that the check valve holds the pressure when the pump shuts off. That doesn't have anything to do with how the engine runs, only with how fast it starts.

6. For the TPS sensor, measure the voltage across the blue and black wires. At closed throttle, the voltage should be between 0.20-0.90V. The PCM checks the voltage at startup, and sets whatever it sees as the "0%" baseline voltage and pro-rates from there for percent throttle opening. Stock, unmolested sensors generally read about 0.65-0.67V. Some people feel there's something special about setting it so a specific value like 0.50V, but I've never found that to be the case.

The correct way to set the voltage is to start by looking at the IAC "counts" (requires a scanner), and adjusting the throttle stop screw so that the engine is at the programmed idle speed, and the IAC counts are in the range of 20-40. Then check the TPS voltage, and rotate the sensor until the voltage is within the specified range. Why did you slot it, if you don't know how to set it?

While checking the voltage, rotate the blades open slowly, and watch for any sudden changes in voltage. The transition should be smooth, with no "blips". The WOT voltage shoudl be ~4.0V higher than the closed throttle voltage.

Not likely that the TPS sensor is causing the problems.

9. Your fuel pressure is probably set incorrectly. What did you tell your "tuner" the fuel pressure was? He had to know that to tune the engine. Why would you "screw it down all the way", without knowing what the correct pressure is? Makes no sense at all. You don't even need an adjustable FPR.

At idle, pull the vacuum compensation line off the FPR, plug the line to prevent a vacuum leak, and set the pressure at 43.5psi. This assumes that "tuner" thought you were running "STOCK" pressure. If you told the tuner you were running 50psi, he would have adjusted the injector flow constant for the pressure.

10. Sounds like the engine runs fine until the PCM kicks into closed loop. Have you ever run a data log on the PCM? That would probably shed a lot of light on what's happening.

Pumping the throttle will not affect anything. If you feel it may be "flooding" when warm, hold the pedal hard on the floor when cranking it. That puts the PCM in "clear flood" mode. Pumping the pedal is a placebo.

Is your "110 octane gas" leaded? If so, its screwing up your O2 sensors. What is the dynamic compression ratio (DCR)? It would have to extremely high to justify 110 octane. What fuel did the tuner tune it for?

95Blackhawk

Joel,

I cannot emphasize enough that you need to datalog. You have thousands of dollars and many hours into this car but no way to diagnose issues such as this.

Go get the laptop, connection and software. You will find this much easier to deal with.