So I've seen this mentioned a few times and I'm lost on what suppose to happen. My question is if you dont have the plates what rpm is the spark advance suppose to happen. O have a tuned gt but I feel like my tuner did a bad job. I made ok #s but its not a aggressive tune I wonder if this could be the issue too
imrc spark advance? need info
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Are you asking for the spark tables for the IMRC's when open? If so, stock, blown, or N/A?
Which PCM are you using, the GT or the Cobra?
The GT PCM doesn't have IMRC tables but the Cobra PCM does.
Since you are running a GT PCM, there is nothing related to IMRCs in the tune, so the IMRC delete is not causing your issues.
The spark advance should be coming from the borderline knock tables, and they will be set up the way your tuner set them up.
The spark advance should be coming from the borderline knock tables, and they will be set up the way your tuner set them up.
Ok. With a stock Cobra PCM and motor, the PCM opens the IMRCs at 3250 RPM, and adds spark advance from the IMRC tables to the spark advance coming from the borderline knock tables. If you do an IMRC delete, and don't use a new base tune with a borderline knock table set up for no IMRCs, then your borderline knock table will not have enough spark advance to make much power.
But since a GT engine doesn't have IMRCs, it doesn't have IMRC spark tables to add. So you are not losing anything by having done your IMRC delete because the PCM has no way of doing anything about IMRCs.
So your IMRC deletes are a red herring. All it is doing is confusing the issue.
It sounds like you suspect your tuner has done a bad job of tuning. There are plenty of things he could have done wrong, but IMRC deletes have nothing to do with it.
But since a GT engine doesn't have IMRCs, it doesn't have IMRC spark tables to add. So you are not losing anything by having done your IMRC delete because the PCM has no way of doing anything about IMRCs.
So your IMRC deletes are a red herring. All it is doing is confusing the issue.
It sounds like you suspect your tuner has done a bad job of tuning. There are plenty of things he could have done wrong, but IMRC deletes have nothing to do with it.
Fuel doesn't burn instantaneously. As it burns, the pressure in the cylinder goes up until the fuel starts to burn out, and the piston moves down. The trick to getting the timing right in the tune is to get the maximum cylinder pressure to occcur at the optimal crank angle for torque.
If the spark is fired too late, (not enough spark advance) the peak cylinder pressure happens too late for maximum torque on the crank, and the energy is wasted. If it is fired too soon (too much spark), a lot of the energy goes straight down into the piston, rods, bearings, crank and main caps, which is hard on them. Also if it is fired too soon, detonation can occur. Detonation is an uncontrolled explosion of all of the fuel at once. That creates wildly high cylinder pressures and breaks ring lands and blows head gaskets. This is not good for any engine, but is particularly bad for FI engines.
In both cases, spark too soon or spark too late, you lose horsepower. Spark too soon and you lose horsepower and you can destroy your motor.
If he told you you had too much timing, he was telling you your motor was at risk for detonation.
If you really want to understand this stuff, read this book: Amazon.com: Engine Management: Advanced Tuning (9781932494426): Greg Banish: Books
If the spark is fired too late, (not enough spark advance) the peak cylinder pressure happens too late for maximum torque on the crank, and the energy is wasted. If it is fired too soon (too much spark), a lot of the energy goes straight down into the piston, rods, bearings, crank and main caps, which is hard on them. Also if it is fired too soon, detonation can occur. Detonation is an uncontrolled explosion of all of the fuel at once. That creates wildly high cylinder pressures and breaks ring lands and blows head gaskets. This is not good for any engine, but is particularly bad for FI engines.
In both cases, spark too soon or spark too late, you lose horsepower. Spark too soon and you lose horsepower and you can destroy your motor.
If he told you you had too much timing, he was telling you your motor was at risk for detonation.
If you really want to understand this stuff, read this book: Amazon.com: Engine Management: Advanced Tuning (9781932494426): Greg Banish: Books
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Not a lot. They typically show AFR but not spark. It would be better for me if you could post a datalog of the WOT run along with the Dynojet file, assuming you were on a dynojet dyno.
But even that won't help a lot. The typical tuner gets the MAF transfer function dialed in with the spark retarded, then sets the target AFR, then adds timing back into the tune until it starts to detonate or until it stops making more horsepower. Then they back it off a couple of degrees for safety and they are done.
What makes you think your tuner didn't do a good job?
But even that won't help a lot. The typical tuner gets the MAF transfer function dialed in with the spark retarded, then sets the target AFR, then adds timing back into the tune until it starts to detonate or until it stops making more horsepower. Then they back it off a couple of degrees for safety and they are done.
What makes you think your tuner didn't do a good job?
that is a low rev limit..
dyno numbers are just relative numbers. did they do before and after pulls for comparison?
weigh your car and take it to the track, your trap numbers are a better indication of the power youre making.
dyno numbers are just relative numbers. did they do before and after pulls for comparison?
weigh your car and take it to the track, your trap numbers are a better indication of the power youre making.
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