well, as some of you know I have been struggling with some problems ever since removing my air pump. Although I believe the problems are not entirely related, it is worth mentioning. anyway, I fixed my crazy idle by replacing o2 sensor with the ford escort one, remving a bunch of fuel at idle, and not plugging the pipe that goes to ACV from the pressure pump side of air pump. anyway, I take the car out for some t ests, and the a/f looking like it always did.

I get ont he boost at about 3k, in 3rd was at about 10psi, and bam heard what sounded like a backfire, but not in exhaust sounded like it came from inside the engine. I thought it was wierd, and took a look at knock readings from PFC. 128. ouch that hurts, I babied the car back home and has been there ever since.

the car ran fine after and idle was okay. I assume I detonated the engine. The question is why. I am running same timming maps as before, and even added fuel to 2k, 3k and 4k PIM ranges to try and reduce cruising knock speads, and fact that there is no more airpump.

What is the deal? am I missing something. eveyone I talk to says ahh, just pull the air pump, plug hoses and you are fine. Why did I detonate??? this is scarnig the **** out of me, I really don't feel like slapping a new engien in.

Thanks guys.

 

If you are getting enough fuel, then check the ignition timing on the pfc. Make sure the timing is correct.

 

the timing has not been changed, I also am noticing high knock at top end like 5 or 6k

 

Cold weather greatly increases power and if your AFRs or timing were on the edge, it might push you over.

 

good point chuck, but temps are actually warmer than last time a drove it with no problems. maybe it is that warm bloody air the acv is sucking in? I don't know. right before I removed the air pump I was boosting .92 kg/cm2 on primary turbo, and felt a wierd power drain and acoompying unidentified noise. ever since I haven't been able to boost full on poirmary, only .88 with same settings. and secondary terible slow to build. I am thinking this may be related. I am going to pull UIM, rack, etc. this weekend and have a peek. good time to repalce stock wires with magnecor since I have HKS TP now.

thanks guys.

 

Try doing Robs seq turbo sys simplification mod. I've done it and really like it. You will need to make (or buy from Carson/Spyfish007) some block off plates.

It removes pretty much everything except whats needed for the seq system. You can even ditch the rack.

I think that will help you problem.

Are you sure that you car detonated? Maybe it just backfired thru the pipe that wasnt capped off.

Later,
STEPHEN

 

The ACV and air pump only supply air to the exhaust manifold and to the main cat. The system is in no way connected to the intake manifold. If a valve went bad there, it might blow out exhaust into one of the two air pump pipes.


BUT, the EGR valve and ports do connect the exhaust and intake manifold. The metal intake gasket has a very small hole that allows exhaust gas to go to the valve which then goes into the intake. If the egr valve is stucked open and the gasket hole burned out, you might be getting as lot of hot exhaust into the intake. This would reduce power and cause detonation. Remove the egr valve and put a blocking blate their and this will solve that problem.

 

this may sound dumb or unimportant, but when i was boosting one day i heard a nasty POP! i freaked and slowed down and my car ran very little if any boost. i limped her home and looked around thinking i popped the motor. later on i found out the intercooler hose going from the metal upper section(from y pipe) to the intercooler had burst open and had a 4+ inch gap i could stick my hand in. i replaced it and no more problems.

i dont know if this means **** here but i thought maybe i should share it with you guys.

 

I wonder if it was fuel system related.
After washing my engine, I once noticed that my fuel pressure dropped below 20psi. I drove back home without boosting.

The next day in the morning, the problem was gone. The only thing that I could think of was the fuel pump resistor got too wet and finally dried out. I noticed this because I have a fuel pressure gauge.