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View Full Version : knock problem or false knock


jds
05-12-2005, 09:43 PM
My 87 ttype has 128,000 on it. put away for winter running great, got it out spring cleaned it and now I have a knock issue. intermittent, and if you sneak up on the boost it doesn't knock, if you jump on it, I have seen as high as 5.5 on the scan master o2's are always in the 800's. dont hear anything odd no popping or anything, I have checked the downpipe and exhaust, its not hitting, checked the torque converter bolts(all tight). I put new plugs and wires on it, installed a adj. fuel pressure reg and a gage, and also put a new hotwire kit on it. The previous owner told me it has a ATR pump in it. I had a red 93 chip in it and the bl was always down around 105-110, seems awful fat to me, tps is set correctly along with iac, the o2 cross count rolls through in about 30 seconds so I think that is ok. I put my thrasher chip in it to see if that would make a difference, and it holds the bl at 128 during idle(which the red chip wouldn't) but when driven it also ends up running bl around 105-110. I increased the static fp to 45 to see if that would make a difference and it made the knock worse and it stumbled a little when driving around 25mph through town. Also, the fuel pressure drops to 0 in about 20 seconds after the car is shut off. I just found the fuel system check up here and will trouble shoot tomorrow. It has new 36 injectors in it and new fuel pressure reg. I'm leaning towards the pump. Sorry this is such a long tread but can all this be related or am I looking at 2 seperate problems, knock and fuel system. can a to rich setup cause knock? also the egr, can this be coming into play here? thanks for your thoughts. Jeff

Drivenmenuts
05-13-2005, 10:27 AM
Fuel pressure shouldn't bleed down that quick after shutdown. Maybe a few pounds after 20-30 minutes, but not as drastic as you describe. Assuming the new injectors aren't leaking I would look at the pressure regulator. Is there any fuel in the vacuum hose indicating a bad diaphram? You might have a bad injector though.

jds
05-13-2005, 08:58 PM
I trouble shot it today and it is the fuel pressure regulator, brand new accufab(I called and they want me to send it to them) I put my old 237 back on and it holds pressure forever. pretty disappointed. I'm still wondering if that pressure regulator could have been causing my knock and fat blm's. any idea's? or what else should I be looking at. thanks Jeff