Recently dropped in a new mild streetported motor in m 93.
I have been keeping the boost under 5 PSI for 500 miles so far, trying to brake it in properly.
The PROBLEM:
The car will no longer start, hot or cold, and when it does get running, it will not idle anywhere below 1500 RPM's without getting real lumpy or shutting off.

It will run fine above 1500 RPM's, and drives fine also. It started great the first 300 miles or so on the motor, with no hesitation. Now it cranks over, gets REAL close to starting, and then bogs back down. It almost seems too rich, but why would it have changed in the last 200 easy going miles??? The idle for the first 300 miles was dead on at 1200 RPM's, and never moved.....

Someone Please help me!!!!

It does have the Rotary Performance High pressure bolt in fuel pump, and the double throttle control, and butterflies were eliminated years ago. It is also running a greddy elbow with 2 additional injectors controlled by a Greddy Rebic 4 fuel computer, but it is turned off, and the injector plugs are pulled(to eliminate them as a problem). Those are the only fuel system mods i can think of.


What could have changed in the last 200 miles to make the motor run and strt so hard now.....Throw out any ideas......

Whoever gives me the answer i need to a great running motor, I will paypal $50 bucks to!!!!

I am checking some vacuum lines later today, so get in your ideas now!!!

Thanks
Shane

 

OH yeah, also put in 4 new plugs and new wires yesterday.
Thanks

 

you have a vaccum leak some where u can bet on that... redo the upper and lower intakes make sure they are sealed right and use the right gasket maker orange is the best in my eyes

 

vacuum line to MAP sensor or electrical connector on the MAP sensor?

electrical connector at the TPS

electical connector at the Idle air control motor?

failed check valve in the map sensor vac line?

Stock ECM or something that you can monitor?

 

could also be a problem with one rotor not sparking properly, it would even out higher revs as the inertia gets great enough to overcome the jerk of only a single rotor sparking and the weight of the two would balance it out.

Check the spark on both leading plugs, check for vac leaks to MAP sensor and in your intake, compression test it and check fuel is getting into both rotors.

good luck!

 

You guys are FAST today!

Where is the idle air control motor. The rest, i will check.

Also, when i was playing with the idle, to get it running smooth, i moved the 8mm nut, and turned in the throttle set screw a bit to get the idle up to where it was needed, but i also messed with the 8 mm nut on the top left of the throttle body that controls how far the 2 top butterflies open and close. Any ideas of where that should be set too???
That answer isnt for the $50 bucks though.
Thanks
Shane


Car and details can be seen here:
http://www.geocities.com/skeppley.geo

 

IAC is on the throttle body - bolts on with two 10mm nuts I believe - I think it is on the opposite side from the TPS - can't remember - but you'll find it

 

Just a shot in the dark, but you said the fuel computer was off? I think you've been running way rich. Possible build up. Don't know if it can happen that fast. I hope it's the MAP sensor for your sake.

 

You tell us. What was the very last thing you did to the car before it started doing this?

Is it hard to start when it's Cold? Warm? or both?

 

It is hard to start when it's hot and cold.
The last thing i did was take a long ride to Maryland and back to PA to put some miles on it. Its was all moving traffic, no stop and go. I got to my house here in PA, put in the clutch to stop, and it simply shut off. Then tried starting, and no go. Had a friend push me down a hill, and let the clutch go, and it fired up, but wouldnt idle well anymore. Pulled into the garage and shut it off, and now it is VERY hard to start hot or cold. Put in new plugs, no difference.

 

Do a compression test. I hate to mention it, but you may have a blown seal.

 

Pull the Circuit Opening Relay, take the plugs out, dry them off, spin the motor over, reinstall the plugs and crank it. It's flooded. If it's way too flooded throw some ATF in there.

Richard

 

sounds like a blown seal to me. compression test will tell for sure though.

 

when you changed the sparkplugs and wires did you triple check that you had them installed correctly?

 

what about spark plugs is it the right temp check that

 

what ECU are you running?

 

do a compression test.

 

wow. Why is everyone so quick to say its blown. Jeesh.

Mine did the same thing and it turned out to be the water thermosensor and I had bypassed (accidentally) the fuel pressure solenoid (PRC). I went through 120 spark plugs from ~700 miles - now. I am happy to say that it is fixed, but I spent countless hours thinking that it was a blown motor before it even saw boost.

so check the water thermosensor (2-pin pea green connector on the back of the water pump housing)...although it might be a brown/yellow color from all the heat and whatnot.

 

OK, checked all the vacuum lines(OK), pulled the plugs, and cranked the motor to be sure they were all firing(OK), Strange thing though, the trailing plugs were black and fouled a bit, but the leading plugs looked like new yet, no carbon or black at all.

Is there anything that could be causing too much fuel to be pushed into the motor?

ALso, when i pulled the trailing plugs,I cranked the motor and had steady whistles as each compression passed in the front and rear rotor. Didnt get out the gauge yet, but it does sound OK.

I have the Pettit Unlimited ECU.

Will also check the water thermosensor as described.
Thanks....
still looking......

 

One of your primary injectors is stuck open.

 

Is there anything that could change the timing on the motor?
Is it possible for the crankshft pulley to move, or slip making the timing off?

Just looking for other ideas.

 

check your fpr. and were the injectors cleaned before putting them in? are they stock?

 

The injectors are all stock, not been cleaned. Only the injectors on the Greddy Elbow are new, and i havent used them yet.

I will read up on how to check the regulator
Thnaks

Also will check on the stuck open injector....
Thanks

 

also doubt this is it, but check the placement of the injectors, to make sure prim and secon werent switched.

 

do you still have the stock ECU? Did you try swaping it? Also check your coils