Tuning gremlin - falls flat at 6200
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TECH Enthusiast
Joined: Jan 2012
Posts: 557
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From: Bowling Green KY
Tuning gremlin - falls flat at 6200 Well I've been working my tune on my car, with good progress, I have it dialed in pretty well under most circumstances. I've dialed in my idle, tuned my VE table, and MAF. I'm still using the stock timing map. I'm having a strange thing happen though. At about 6-6.2K (as read from the engine log, the tack is reading about 5k) on a WOT pull the thing falls flat on its face. From the log I can see the fuel is being shut off, as the afr on my wide band goes from about 12.5 to 20+ instantly. I have the rev limiter set at 6700. The oil level light flashes, although oil pressure is fine, the fuel gauge goes to full, even though I have about a 1/2 tank of fuel, and the idle goes up to about 2.5k until I shut the car off and restart it. If I shut the car off and start it it goes back to normal, idle and fuel level. I have replaced the oil level sensor in the pan since this oil level light flashed upon the problem. Anyone have any ideas? All of the wires look ok on the oil level sensor?
My start up modifiers RPM are at 6300, that's the only thing close to the point this is happening at?
I'm just going to keep searching and trying things to locate what is going on, but I was thinking someone may have experienced or know whats happening.
My start up modifiers RPM are at 6300, that's the only thing close to the point this is happening at?
I'm just going to keep searching and trying things to locate what is going on, but I was thinking someone may have experienced or know whats happening.
Do you have any speed sensor issues? Check over the tables for rev limiters other than the standard in gear limiters - if you have any speed sensor signal issues, it will use different limiters - you may be hitting those...
Thread Starter
TECH Enthusiast
Joined: Jan 2012
Posts: 557
Likes: 9
From: Bowling Green KY
Please see attached tune and log, I have not had much time to work on it lately, I've been asked to work 12 hr shifts, 7 days per week for the time being. Any suggestions are welcomed. Thanks.
5-23-12 test tune.hpt
5-23 drive.hpl
5-23-12 test tune.hpt
5-23 drive.hpl
This sounds like an electrical fault that's bugging multiple
sensors. Might be the alternator skipping, belt slip etc.
and a battery that sags too much? Do you have system
voltage logged?
sensors. Might be the alternator skipping, belt slip etc.
and a battery that sags too much? Do you have system
voltage logged?
Thread Starter
TECH Enthusiast
Joined: Jan 2012
Posts: 557
Likes: 9
From: Bowling Green KY
Thanks Jimmy, this is the type of help I was looking for on this one. I know the tune is not dialed in 100% yet, but it is close enough that I don't think it is the problem. Here is a little more history. I did a head/cam swap on the car, thus the need for the new tune. I also swapped to poly motormounts while the heads and headers were off the car, so I removed my AC unit, and alternator for access. I cleaned and detailed everything while it was apart. After putting it all back together, and firing it up, my car was running at 18 volts. I think that cleaning or handling the the alternator somehow wrecked havoc with the voltage regulator in it. I bought a brand new delphi alternator, and a new tensioner and pully, and installed that. Fired it up and it reads a constant 13-14volts on the voltage gauge, so I thought that the problem was fixed. I guess that firing it up at 18 volts could have fried somthing? But it runs fine below 5K rpm? Any other ideas about what I should check next, or suggestions about how to troble shoot this one? I'm thinking that since it is the oil level sensor, fuel gauge, and the idle air, that all go whackey they must be tied together some how? And a shut down and restart fixes them all. I truly belive I have an electrical problem rather than in the software of my tune, but was looking for trouble shooting help.
Based upon what Jimmy said I'll log some system voltage and see if it agrees with the gauge, as well as maybe replace the battery and the main belt that turns the alternator/PS and waterpump? I hate to just throw parts at it wish for it to be fixed? I was hopeing that somone may have seen somthing similar before and have some suggestions about what electrical problems may have caused the specific symptoms I have.
Thanks for the responses folks.
Based upon what Jimmy said I'll log some system voltage and see if it agrees with the gauge, as well as maybe replace the battery and the main belt that turns the alternator/PS and waterpump? I hate to just throw parts at it wish for it to be fixed? I was hopeing that somone may have seen somthing similar before and have some suggestions about what electrical problems may have caused the specific symptoms I have.
Thanks for the responses folks.
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Thread Starter
TECH Enthusiast
Joined: Jan 2012
Posts: 557
Likes: 9
From: Bowling Green KY
Just for the record, incase anyone searches and finds this thread in the future. The problem was a poor ground. An extra 1/4 turn on one of the grounds on the back of the cylinder head on the drivers side fixed the problem. The car pulls great now all the way to 6.7k where the rev limiter is set. What made it hard to track down was that the problem was intermittent and only evident at high rpm.
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