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Discussion Starter #1 (Edited)
Well I thought I would share this problem since my install of my on3 kit. I bought the car in February as a bone stock 95gt. And only test drove it...Didnt really get on it cause there was snow on the ground. Problem Im having is the car breaks up slightly at about 5000rpm..Running about 7psi now and I have put on a Crane cam fireball box and coil on. Also my tune according to my datalog is pretty safe. 17-18 degrees of timing when I'm into boost and my AFR is reading about 11.9. I set timing at 10deg base with pill pulled. Also I ran race fuel just to make sure I wasn't detonating and problem still occurred. Could the problem have existed when the car was stock? Could my distributor PIP(I think that's what its called) be bad? Also what about the remote module? I do have a distributor on order. Any help would be appreciated. setup is in sig....Oh for got to mention Im running 60lb injectors with pressure set at 38lbs with vacuum hooked. Autolite 103 plugs gapped at .028, I also tried NGK t5's I think thats what they are. Everything looks good on datalog. TPS is 4.77volts at wot and MAF sensor voltage is 3.2 and reading is about 1100.
 

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Discussion Starter #3
made changes to post.....028
 

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I had to gap my plugs to 15. I would make sure your not losing fuel pressure under boost. I had a one that would do the same thing. The pressure should spike up and hold while in boost. If it drops off possible fuel pump not enough.
 

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Discussion Starter #5
Fuel pressure is 39 at idle with vacuum hooked up. 50psi when under boost. Also i forgot to mention that I have a walbro 255 pump.
 

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Discussion Starter #7
I thought that too....I just changed it today. It's still breaking up. I thought about turning up the fuel pressure 5lbs.
 

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Not knocking your tune, but 17-18 degrees of timming wide open is super low, really low if your running racegas... I would try and take the car to have a chip burnt for it on pumpgas, the car will run so much better down low,(idle right) and have enough timming to rev all the way out... Im sure you know the 94-95 computers arent the easiest to try and do a manual tune like the foxbody cars...
 

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ok i just seen you have the Moates, try and adding 1 degree of timming and make a pull see how it does, and repeat..
 

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Not knocking your tune, but 17-18 degrees of timming wide open is super low, really low if your running racegas... I would try and take the car to have a chip burnt for it on pumpgas, the car will run so much better down low,(idle right) and have enough timming to rev all the way out... Im sure you know the 94-95 computers arent the easiest to try and do a manual tune like the foxbody cars...

My car is tuned with 18 degrees total timing, granted im running 11-12lbs of boost but I dont have an issue with breaking up. I dont think that timing has anything to do with his problem. Its more then likely a fuel issue or spark blowing out but with only 7psi boost the spark should not be blowing out
 

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the issue i had with my car breaking up was in the mass air meter. i have fixed that issue but have not even tried to get the car in boost but once and ran great
 

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18 degress timing is too low for 7 psi, bump it up to like 25* total under boost, not that it will fix your break up but you never know.

Check your plugs, i know ive got too agressive with my tuning sometimes and burned straps off plugs before causing a bad miss.
 

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Discussion Starter #14
I pulled all the plugs and checked them....All looked good no signs of detination. Also they were nice and tan. Were yellow when running straight race fue. Im leaning towards the distributor pickup is bad. I just changed the filter and it still does it. ( have a 255pump). Ive tried going up and down on total spark but only as high as 20 degrees total. What about fuel pressure Gage says its about 47-50lbs when into boost. Could the module be bad? Thanks for the suggestions keep em coming
 

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most of the time when a module is bad they just quit, but they are cheap and worth a swap.. check all of the grounds on the mad box or what ever you are running...
 

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Id do a few things;
1. thighten the gap on plugs (Id get autolite ididiums($7.99) gap to .020)
2. swap in a stock distributer

are your vavle springs upgraded? could be valve float causeing breakup above 5k
 

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Discussion Starter #18
valve springs are upgraded.....with alex's spring kit..
 

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I wouldn't spend money on iridium plugs until you have the tune nailed, if at all.

Autolite racing plugs work well and are cheap. .020 sounds a bit tight on your setup but that is a free test.

Weak valvesprings can definitely cause breaking up.

Checking grounds is also a good suggestion as a boosted motor is more sensitive to quirky ignition issues.
 
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