Car keeps cutting out.
05-04-2010, 08:59 AM
#1
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Car keeps cutting out. I have a 1994 Camaro with an LQ4 swap GM Hotcam and completely wired the ECU myself. I wired the ECU to be a 2000 Camaro and am using HP Tuners which reads the ECU as a Silverado if that matters. The Ecu is out of a 2000 silverado 2500 HD and is tuned to be an LQ4. It has factory 28 lb/hr. camaro injectors in it.
On startup it sometimes starts hard and I have to feather the throttle to keep it running.
On Idle it feels like it's skipping a beat.
When giving it gas down the road it feels like it's missing a beat as well but when I get into it the car feels like it wants to go but then starts missing and feels almost like it's lacking fuel / spark or something. The higher the rpms the worse it feels.
I know this is vague but does anyone have any ideas.
On startup it sometimes starts hard and I have to feather the throttle to keep it running.
On Idle it feels like it's skipping a beat.
When giving it gas down the road it feels like it's missing a beat as well but when I get into it the car feels like it wants to go but then starts missing and feels almost like it's lacking fuel / spark or something. The higher the rpms the worse it feels.
I know this is vague but does anyone have any ideas.
05-04-2010, 12:43 PM
#4
Remove and reseat them listening for an audible click over the plug and two clicks over the coil end
If the problem persists, remove and do a continuity test across them. The ones Ive checked were usually around 470ohm. If they are all within about 30 ohms of each other then move on to other possibilities such as plug gap and proper grounding of the coils
If the problem persists, remove and do a continuity test across them. The ones Ive checked were usually around 470ohm. If they are all within about 30 ohms of each other then move on to other possibilities such as plug gap and proper grounding of the coils
05-04-2010, 12:58 PM
#5
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Thats what I'll do. I'll test the wires tonight. If they're good i'll go to the coils and re-ground them and add a chassis ground for reassurance. What should I check the plug gap to be? I want to say I gaped them at about .050 or something in that realm. I think I have the T5 plugs if I recall. It's been almost a year since i've put them in when I was piecing the car together.
05-04-2010, 02:14 PM
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True very true... I'm going to check those things and go for a datalog run. I know i'm getting voltage drop under throttle. The more rpms i run the less voltage I run.
I don't know what the fuel pressure is doing under throttle but just revving it stays @ 50.
I don't know what the fuel pressure is doing under throttle but just revving it stays @ 50.
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05-06-2010, 12:31 AM
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Here's what happened tonight. Still not running right.
Car seems to idle okay. Seems to hitch or miss every now and again.
I added another battery ground wire, added 2 engine ground wires from each cylinder head to each strut tower, tapped into the ignition coil Black wire coming out of the harness on top of each coil module and grounded them to each of the grounds on top of the strut towers. Still having the same problem missing etc throughout the RPM range. The more gas I give it the worse it gets. The warmer it is the more noticeable it is cruising especially.
I checked all of the plugs and wires. All of the plugs look fine. They are TR5 plugs gapped @ .038.
I tried testing ohm's on the plug wires and they're all different however I tested my buddies and they were all completely different as well and those ones run his gto beautifully.
I tried datalogging and i'll try to get a snapshot of one of the runs up.
What's next?
Car seems to idle okay. Seems to hitch or miss every now and again.
I added another battery ground wire, added 2 engine ground wires from each cylinder head to each strut tower, tapped into the ignition coil Black wire coming out of the harness on top of each coil module and grounded them to each of the grounds on top of the strut towers. Still having the same problem missing etc throughout the RPM range. The more gas I give it the worse it gets. The warmer it is the more noticeable it is cruising especially.
I checked all of the plugs and wires. All of the plugs look fine. They are TR5 plugs gapped @ .038.
I tried testing ohm's on the plug wires and they're all different however I tested my buddies and they were all completely different as well and those ones run his gto beautifully.
I tried datalogging and i'll try to get a snapshot of one of the runs up.
What's next?
05-06-2010, 02:41 PM
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plug wires When I tested the plug wires I had 1 around .470, 5 around .960, 1 @ .999, 1 @ 1.050. My buddies were all over the place and work well in his car. 1.5, 2.8 etc...
05-06-2010, 06:15 PM
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We can't trade wires cause his plugs have 45 boots on bottom otherwise i would've already. I don't know how to get the log up on the forum here. I am seeing that my o2's are all over the place under wot. My injector % also seems really really low for what I have done to the vehicle. I'd expect it a lot closer to 80 percent and it's only around 38.
05-10-2010, 02:57 PM
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Bought a new set of wires and put them on with no luck. They also all read different resistances with all 4 of my multimeters.
Onto the next thought? Anyone ? Please?
Onto the next thought? Anyone ? Please?
05-11-2010, 06:59 AM
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I am not sure what the gap is supposed to be. What would a smaller gap cause? I know large gap causes blow out. Does a smaller gap not atomize the fuel properly and burn rich?
I made some logs but can't find a way to post them. My printscreen key doesnt work right on my computer.
I did notice that @ wide open throttle my injectors are only reading 30% duty cycle if that might have something to do with it. I have the camaro injectors 28's and using the silverado 6.0 tune with all of the parameters changed to the camaro's.
I made some logs but can't find a way to post them. My printscreen key doesnt work right on my computer.
I did notice that @ wide open throttle my injectors are only reading 30% duty cycle if that might have something to do with it. I have the camaro injectors 28's and using the silverado 6.0 tune with all of the parameters changed to the camaro's.
05-11-2010, 07:37 AM
#16
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It sounds like you may have a tune problem. Is it going into power enrichment mode? You need to put a wideband on it and make sure it's not running incredibly lean.
05-11-2010, 08:45 AM
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I am not sure how to check if it is going into PE mode or not. I am a complete noob to tuning and HP tuners for that matter. I do not have a wideband yet as I can't afford it right now. Wife made me spend the extra cash on siding. PFFT who needs a good "looking" home when it's functional lol.
I do know that my injectors "should" be damn near maxed out with my setup. When I start leaning into it the car gets to about 2200 - 2500 rpms and pegs the knock. I start with 2, 4, then 10 counts almost instantly. It's rather scary.
I do know that my injectors "should" be damn near maxed out with my setup. When I start leaning into it the car gets to about 2200 - 2500 rpms and pegs the knock. I start with 2, 4, then 10 counts almost instantly. It's rather scary.
05-11-2010, 01:10 PM
#18
TECH Regular
Sounds like you are starving it for fuel big time. Make sure that your volumetric effeciency tables (primary and secondary if your has it) match a stock 6.0 tune. That will give you a good starting point. Also make sure your PE settings and MAF curve match the 6.0 tune. Use the injector values from a stock f-body tune to make sure that is correct too.
I hope you are runnng front o2 sensors. What are your fuel trims? I bet they are very high.
What have you messed with in the tune?
I hope you are runnng front o2 sensors. What are your fuel trims? I bet they are very high.
What have you messed with in the tune?
05-11-2010, 01:39 PM
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My buddy is the one that played with the tune. From what I understand he took the tune that I pulled out of my ECU and converted everything to that of a 2000 Camaro matched it exactly. I guess the tune he copied had my GM Hotcam as well. When I get home i'll have to give it a once over and see what it looks like.
05-12-2010, 12:34 PM
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I am the one that loaded the tune. Everything he said about the tune was correct. Just got a tune from a camaro with a hot cam. We figured with the injectors changed this would be a good place to start but it makes more sense just to copy the injector tables over. The only thing that is weird is that he is only going lean on bank 2. And it spikes then goes very rich then goes very lean again. If it was in the tune wouldn't both banks be lean or doing the same thing?