North American Turbocoupe Organization



Another detonation problem
BigMikeTC Offline
Senior Member
#1
Well while my '87 TC 5sp. gets the body work FINALLY done I have a problem. I had a slight race with a 2005 Subaru WRX STI on the highway and I had him up to about 100 mph (yes I know racing bad on highway). Then I was getting detonation all of the sudden. I was wondering was it from my MSD box giving too much spark, IHI running out of steam, or just plain heat soak from the IC? Yes I have a fresh tune up. Yes I have Autolite plugs and wires. Timing 10 degress spout off. Fuel 42lbs. Gillis set at 18lbs. I know I am going to change to my T3/T4 as soon as the body work is done and the Boost Cooler as well. I just like to know what might be causing it. Oh yeah I do have a AFPR and a 255lph Cobra fuel pump. Also the knock sensor is diconnected because it was pulling TOO much timing before.
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Pete D Offline
Administrator
#2
Quote:I had a slight race
Kinda like being slightly pregnant or a little bit dead?? Big Grin
Detonation is usually caused by lack fuel, too much timing advance, too high a charge air temp or some combonation of the above factors. Pre igntion could also be caused by a hot spot in the combustion chamber, like a sharp edge holding heat or carbon build up holding heat.
I think you can probably rule out the MSD box and the IHI running out of steam.

Heat soak is a possibility. Perhaps a faulty/dirty injector. clogged fuel filter. Have you ever checked the fuel pressure at boost?
Pete Dunham


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BigMikeTC Offline
Senior Member
#3
LOL. Yeah I can say thats right. Well I have NEVER checked the fuel pressure at boost before. When I get the car back I will hook up a fuel gauge and see what it says. What should it be at at boost? The fuel filter is new as well and a new fuel tank and sock. All of the fuel system is new except the hard lines. I didnt want to have to replace injectors until I got the new turbo and FMIC and SDS in but if I have to I will replace them. Who would have the injectors for cheap?
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Joe F Offline
Posting Freak
#4
At boost the fuel pressure should be your base pressure + boost PSI.
JR's Place - My '87 Turbocoupe
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BigMikeTC Offline
Senior Member
#5
So if fuel is 42lbs and boost is at 18lbs then it should be 60lbs correct?
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Pete D Offline
Administrator
#6
Yep, about 60 psi

You could have your current injectors cleaned and flowed. Cruzin Performqnce is good and reasonable.
http://www.cruzinperformance.com/
Pete Dunham


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svo_thunderchicken Offline
Senior Member
#7
cruzinperformance does a real good job, i have 2 sets of theirs..
84 TC Silver 5 speed - PE EEC, Big Vam, RR cam, 35lb injectors, E6 swap, T3 60 Trim, 87-88 intercooler and hood, BOV, K&N Cone Filter *under constrution*
http://www.cardomain.com/ride/2298891/1

87 TC Black 5 Speed - Stock IHI, BCS Bypassed
http://www.cardomain.com/ride/2390431
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