TPS Adjustment? Maybe?

[mikefromMN]

Quick question: Using MMCd on a 1g, should I see the TPS as roughly 10%? or 0%? I've gotten conflicting information, and the cars running like crap.

[19TsiAwd90]

10% on a 1g and 0% on 2g's i think

[mikefromMN]

Would the TPS being out of whack lead to excessive timing advance and knock? What should I be looking at?

[s1ngletracker]

Do you have a factory service manual? There is a quick test you can do on a TPS with a volt meter.

[Halon]

A mis-adjusted CAS could lead to wrong base ignition timing and excessive knock...

[munchgsx]

1G DSMs have excessive timing stock. What all is done to the car? If it is stock then something is going out of wack. If it is modded what are you tuning with?

[mikefromMN]

Base igntion is claiming 5 degrees per MMCd. 39 degrees at 15psi isn't excessive? I'm maxing out the knock sum... Please excuse the rambling post.

This is the car:
http://mitsustyle.com/forums/showthread.php?t=26935

After finding seriously low compression I took it in, bought a good shortblock with 8.5:1 compression ratio pistons, had the head r&r'd, and had it installed. ARP headstuds, good headgasket, no expenses spared, as far as i know.

I'm still "using" the MAFT to compensate for the injectors, although I personally haven't touched it. Would the higher compression ratio affect this at all? I took a day off of work to get it tuned, as much as I can with a MAFT, and when I got there their wideband for the dyno was messed up. The guy was nice enough to take a look at my car and plug in the datalogger cable (long story). He also suggested that I adjust the TPS to read 0%. My fuel trims were close enough, though, so he said that the car should be fine.

I looked around on the net and found something saying due to a limitation in the design, blah blah blah, the TPS should read 10% at idle. So I called the place that put the motor in, and he agreed with the other guy that it should be 0%, but he just suggested I adjust the throttle cables.

I'm personally guessing it's something along the lines of a bad knock sensor, a bad o2 sensor, a massive f'n boost leak, or the MAFT is really that far off because of whatever. The tune the car had on it obviously wasn't good; i had to buy a new shortblock.

Insults? Advice?

[Halon]

Are you saying your running 39 degrees of timing at 15psi? Or ar you saying your seeing 39 degrees of retard because knock is so bad? I'm a little confused there.

And I always check my base timing with a timing light, not via a logger. Ground the timing plug, and shoot a timing light down there and see what your base timing is.

Also, what size injectors are you running? A MAFT will compensate for the larger injectors by tricking the ECU. The larger the injectors, the more it tricks the ECU. You can only trick an ECU so much before it starts doing things it thinks are correct, but may be hurting you (like running excessive timing on top of the already aggressive timing 1G's have).

[munchgsx]

39 degrees wide open? Thats the reason for your knock. Check base timing something is not right. Do like Halon says ground the pin on the firewall and set it with a light. Also check for boost leaks and for a bad knock sensor.
And yes the higher compression engine will mess things up. Get something better to tune with. ECMtuning.com or your

[Halon]

Yeah if you're seeing 39* at full throttle and full boost, that is a redonk amount of timing.

[Shane@DBPerformance]

Do you have a real tuning system for the car? The MAFT is good at converting a GM MAF to work on a DSM, but a very poor tuning device. You usually set the MAFT up like as if the car was stock with with stock injectors and then use a better system to compensate for injector and do actual tuning. The factory ignition timing tables in a 1G are way too aggressive for an 8.5:1 compression motor, unless you are running race gas or E85 and still not going crazy with the boost. Using the MAFT to scale the injectors is making it worse and run even more timing.

[Shane@DBPerformance]

Switch the TPS to read in volts instead of percent. You should be shooting for .63V at idle with the car running and throttle fully closed.