Tuning issues

[mc_h]

I just purchased a supra and it's at the shop having some tuning difficulties...I had originally bought it with a blown HG, it's a 61mm single with a maft pro, 550's, single walbro. It had dyno'd 420whp but supposedly the shop blew it when they raised the boost.

After getting the mhg replaced, it's evident the shop tuned through a problem thus why it blew...The rpm signal to the maft pro is cutting out randomly...So when revving(even not under load), it will hiccup and the rpm signal misses for a split second making it run lean. it will continue to do that randomly

It's got an ffim so they checked the TPS, it's fine...It seems to have been narrowed down to either the maft pro unit itself or the wiring harness. Now, the wiring harness had been redone with some wiring removed by the previous owner - Basically, the shop is saying it's a 50/50 toss-up right now, choose the harness or the maft pro to change out and we can figure out which it is.
Anybody have any input on it?


Thanks
Mark

 

[satx88supra]

Sometimes when buying a project car from others will turn out to be expensive with either money or a waste of your time. If the harness was chopped up I'd go with seein what he took out. If you can't figure that out .......find or make a complete harness. Verify everything is at square one with harness and then trouble shoot your maft pro.

Btw.....is this the same shop that screwed up the first time tuning through athis known issue. If so find another shop

 

[mc_h]

It's a different shop that has worked on many supras in the toronto area...And as for the actual problem, I did have a maft ages ago and it worked; albeit not the most user friendly, but I have a hard time believing that it's the thing that's dropping the rpm signal so maybe I'll just start with a new harness...Might be easier than tearing apart the whole thing and figuring out what was done and if the grounds weren't done right

 

[Supracentral]

Swapping out parts on a coin toss is rarely a valid diagnostic method. Get out a voltmeter and test the wiring. You'll likely find a single short or missing ground.