sub-zero

I have had my rebuilt motor for the last three summers and it has about 4000 miles. It sits every winter (snow) and I just got it out last week. I took it for a couple short drives last week and everything seemed fine. I was running up to 25 PSI with no problem last year and have 10.1 AFR with a wide band and conservative timing. I got on the gas a couple times and yesterday and boosted to a peak of 1.33 bar and had some misfire but I dont think any detonation? The PFC did not read any knock and the injector duties were low, I was running a mix of C14 and premium. When I got off the gas and had let the car idle it was bouncing like nuts. I think I blew a seal but have not had time yet to check compression. The weird thing is that when I shut the car off and resart it it will start fine but the idle ramps way up to 3000 RPM and after a few seconds it will bounce like nuts. I have no ISC or anything that would cause this. I obviously checked the map sensor and it is fine. It is not idling ruff but bouncing and I think I can here something in the motor but the knock is still not there and the sensor has been working fine. I dont have a dealership that has a rotary compression tester but what is the best way to check with a conventional?

Any body that has any ideas I would gladly like to here them as I dont really have alot of free time at home.

Thanks

Steve

LUPE

only 25 lbs? that's weak

Pull one trailing out and listen. You should hear 3 nice swooshes. Do the same with the leading.

Have you checked for vacuum leaks?

sub-zero

If I get time I will check the wooshes as they were very strong before. I have had many problems before but I feel this is it for this one.

LUPE

It doesn't take much to break these motors. You should know that. I've broken plenty of these and I've never heard any detonation. Just blah.

rx7tt95

Check to make sure you haven't blown off a vacuum line or cap (idle leak will cause that) and that all your throttle body adjustment screws are secure. I forgot to do that once and it caused the fast idle screw to adjust itself and screw up my idle. I have the ISC disconnected but if the screws are off, it'll idle like you describe.

SPOautos

I dont normally see one try to ramp up when it blows. I agree that sounds more like a vacuum lleak

Stephen

GUITARJUNKIE28

the only time i've seen the idle ramp or bounce on an fd is when the secondary thrrottle plates get stuck. pop off your tb and clean it out really well. see if that doesn't help.

GQMRacerX7

It sounds like what happens to me and a vacuum line had popped off post TB.

GUITARJUNKIE28

^ good call

RETed

What kinda turbo?
What sized fuel injectors?


-Ted

sub-zero

turbo is a gt 63/67 comp. .96 hotside 750 pri. 1680 sec/ Aeromotive Eliminator pump 55 psi base fuel pressure. I have run up to 26 PSI and have had 89% injector duties.

I think you Guys are right , and will have to take the upper intake off. I did not do the compression check yet but whooshes are as strong as ever. I think I might have blown a gasket out or a block off plate has loosened. I have tried to keep this motor going by being fairly safe with AFR`s and decent timing and am hoping it is the TB or a leak. Thanks and I will update when solved. The 7 has been sponsored by BFG and Castrol this year so this would not be good at all.

Steve

93FD3S

I think 55 psi base fuel pressure is too high. With vacuum source disconnected on FPR should be around 43 psi.

sub-zero

No I need to run that high of base pressure or I wont have enough fuel. My idle was very solid before this. I have seen Guys run 65 base but that is really high. The Aeromotive Eliminator pump is a much better pump then the A 1000 that I had before giving me alot of fuel.

RETed

89% yikes
I think safe is 85%.
If you're consistently getting over 80%, you need to change something.

Yeah, 750/1600 should be good to almost 500hp at the wheels at stock base fuel pressures.
Your turbo can hit 500 at around 15 to 20psi.
These are just rough numbers off the top of my head.
With the bumped up fuel pressure, your capacity goes up to 500 to 550 range.
I think you're playing with fire getting the pulsewidth up that high.


-Ted