Cold start and running problem (Long)

[NOSNotch]

I've got my new motor and all in my coupe and i've yet to have it really runnin right.

First problem is with cold starting; it doesnt want to stay running until it gets some temperature in it. I have to keep feeding it gas and revvin it for a few minutes before it'll hold an idle on its own. While revving it hesitates like it doesnt have any throttle response and it occasionally pops like a misfire.

The other problem is with actually driving it. The car will rev fine just sitting but once you try to go down the road and put it under load it bucks and pops in the exhaust and then if you mash it a bit it seems like it'll clear out. Sunday night I tried to get it runnin right and i pulled the distributor, spun the motor around to TDC and dropped the dist. back in, took it up the road and it seemed perfect, no popping, no hesitation or nothing but then today I brought it in the shop to swap the 5 lug axles in and then got it warmed up and went to take it down the road and the same b.s. with the hesitation, bucking and popping

I really dont know where to go with this so I'm open to any suggestions. If I cant figure it out I'm ready to sell the EFI stuff and just put a carb on top.

Kevin

 

[HISSIN50]

have you pulled codes? cleaned/replaced the IAC? checked the ECT and ACT values? checked for vac leaks?

good luck.

 

[NOSNotch]

It has a new IAC on it and I adjusted the TPS voltage as well. No vacuum leaks and no codes I didnt expect (smog, purge solenoid, egr control solenoid) I was thinking it could be a problem with the ECT since that is really the only sensor that is not new. I couldnt get any data from the scanner so I was considering changing out the ECT and seeing what happens. I'm not sure what the ACT is though? Any other suggestions?

Thanks
Kevin

 

[5spd GT]

Well on the cold start problem...here is what I did to fix mine...

I replaced my plugs (proper gap)/FRPP 9mm wires/OEM rotor and cap/ and cleaned the IAC REAL good with carb cleaner/clean the MAF/cleaned the throttle body with carb cleaner...and that was that...I have no more cold start problems...might want to change a few of those little things and see if that helps...

 

[Michael Yount]

What do you have the static timing set at? Tell us more about the combo - static compression ratio, cam specs, injector size, etc.

 

[Michael Yount]

The ACT is the air charge temp. sensor. It screws into the #5 runner on the stock intake - tells the ecu what the air temp entering the engine is. ECT is engine coolant temp. Bad ACT usually doesn't affect cold start as much as a bad ECT does. You need to pull the codes.h

 

[HISSIN50]

I'm not sure what the ACT is though? Any other suggestions?

Thanks
Kevin

Kevin, ACT = Air Charge Temp sensor.
it and the ECT can be likened to having the same affect as a choke on a carb.

i might add: i would not use carb cleaner on the TB. it is coated with teflon - carb cleaner can eat that coating off. most Throttle body sprays omit the ingedients which eat the teflon.

good luck.

 

[NOSNotch]

Ok I have a new IAC, new plugs, wires, cap and rotor, new tb and new MAF so I've already kind of eliminated them as the problem

My timing is set at 14 with the spout out. As for the motor its a 306, 10.5:1 compression, ported twisted wedges, 1.6 comp cam rockers, tfs street heat intake, 70mm tb, 30lb inj, 255 pump, 75mm Pro M, Kirban regulator, Comp Cam custom grind cam, my card was "misplaced" by my ex so I dont have all the specs in front of me but it has like a .560 lift. All this in a '93 coupe with an A9L (no chip or extender) and using a 93 engine and injector harness.

I thnk i'm gonna try to replace the ECT today just for fun and see what happens. As for the ACT though, I dont have it nor do i have a plug on the harness that would go into it, i thought they didnt start using them until 94-95?

I'm off to work and i'll try dealin with this thing after, keep the suggestions coming guys. Thanks

Kevin

 

[Michael Yount]

I think we've all suggested pulling the codes - don't think you've responded to that yet. They're there to keep you from simply guessing and continuing to replace parts that there may be nothing wrong with. Autozone will usually pull them for you for free. Edit - sorry; just saw you didn't get any you didn't expect.

 

[5spd GT]

i might add: i would not use carb cleaner on the TB. it is coated with teflon - carb cleaner can eat that coating off. most Throttle body sprays omit the ingedients which eat the teflon.

Hmm...I didn't know that...my TB has been on for quite a while on my car...probably a few years...I didn't see anything "on" it...but I shouldn't expect to see a coating...I just know I sprayed it down with carb cleaner and used a Q-tip in the small areas and it got a lot of build-up off...made it look much better...

 

[NOSNotch]

Sorry bout that last post guys. I do have the ACT sensor i was looking around where the stock airbox would be though didnt know it was in the intake. I put the scanner on the car again today and wrote down the codes just so I could clear that up;

neutral switch ckt problem (used to be auto, had to bypass neutral safety)

thermactor bypass somethin (b/c all smog stuff is gone i assume)

canister purge ckt problem (plastic line from tank is there but nothing else)

egr control solenoid ckt problem (also not there)


I never got the chance to get up to Ford today and get the ECT but I'm gonna try that tomorrow, since the car really only acts up under load can the ECT be to blame or would i have a problem at all times if that was bad?

One of the other guys at work said to try hooking vacuum to the EGR to see if it made a difference and nothing, i didnt even think that was an issue but that'll pretty much eliminate that

 

[Michael Yount]

If the ACT/ECT were bad, it would throw a code. I wouldn't replace it needlessly. Don't understand the egr/vacuum test. I thought the egr had been removed. If it's been disconnected, but is still present, and if you're trying to determine if the egr valve is leaking exhaust into the intake, since you've got it uplugged anyway, I'd remove it and make a plate out of aluminum to seal the hole.

 

[NOSNotch]

Well over the weekend I put a new ECT in, thought maybe it might be partial to blame for the cold starting, also got a new ACT and plugged it in w/o installing it b/c i figured if the original was way off if the new one was just in the atmosphere it would make the difference if that was the problem. Well the ACT made no difference so I'm using the original. I put the breakout box on and all the voltages seemed to check out. I jacked the fuel pressure up to around 46 and the car seemed to straighten out for about 10 minutes. Then right back to the same stuff. I tried another computer today with no luck and also another distributor with same results. i'm just about fed up and headed towards goin carb'd since my buddy is about to start parting out his coupe and I could get his carb setup at a good price. Any other things I should check or try to fix? Also before I go carb is there anything that doesnt have to do with the EFI I should check now that way I dont switch to carb and experience the same problem? Thanks for all the help guys

Kevin

 

[5spd GT]

Try some of those things in my original post...it solved my cold-start problem I had for over a year...

I wouldn't convert to carb...personally...

 

[NOSNotch]

Thanks for the advice 5spd GT, Most of that stuff wont apply to me b/c it's all new, New IAC cap rotor and FRPP wires as well as new autolites gapped correctly and the tb is brand new as well. I dont really know where else to look and after the amount of time it took me just to get the car together I really wanna drive it not put another two month into it just getting it to run half decent ya know

Kevin