surging?

ujslost · 06-20-2005, 05:51 PM

Ok guys got the motor in finally, been driving it around last 2 days, trying to get the computer to learn its stuff again.
Well Its got a problem that pisses me off,
heres what we got here.
timing is on 15-16 degrees btc
trickflow stage 1 camshaft
when i crank my car it acts like its carbed, wont run hardly, after i drive it a min or so its ok, whats pissin me off is this
after its warmed up and i stop at a light, it idles high for a min or so, then sometimes it idels down and sometimes it doesnt. I can come home cut it off, let it sit 5 mins, crank it and it idles around 1200 rmp or so, drive it stop let it idle, idles at almost 1500 rpms. I have tried to idle it down with the idle screw, but at 900 rmps it sounds like its about to die, (possibly just sounds this way because the cam is loping harder at a low rpm)
basically i want it to idle right, this idleing high and the low pisses me off, i want to hear the cam when im sitting still, and with it idleing high i cant and it sounds like crap.
I havent checked the TPS yet didnt think i should since, i didnt remove it from the throttle body.
I had this problem last time i put heads and crap on, i cant remember for the love of god what i done to fix it
Friggin check engine light is on also, could it be because i removed the factory temp sensor, and installed a mechanical temp guage?

Wicked · 06-20-2005, 06:44 PM

Quote:

Originally Posted by ujslost

Friggin check engine light is on also, could it be because i removed the factory temp sensor, and installed a mechanical temp guage?

Is the IAC hooked up? Maf?

The factory temp sending unit in the left front of the lower intake only controls the gage, one wire. The sensor in the coolant tube on the right side of the intake (two-wire) is for the engine ECU. If you change it out you will screw with teh ECU.

Without the ECT your engine may be running in open loop constantly which may be the reason for the problems.

ujslost · 06-20-2005, 07:04 PM

nope not the ECC coolant, i changed the correct one, the one beside fuel injector driver side, all the other crap is plugged up

Wicked · 06-20-2005, 08:00 PM

Quote:

Originally Posted by ujslost

nope not the ECC coolant, i changed the correct one, the one beside fuel injector driver side, all the other crap is plugged up

Then I don't think thats at all a problem.

If your engine light is on, check your codes. The code may shed some light.

QWKSNKE · 06-20-2005, 10:01 PM

Quote:

Originally Posted by Wicked

If your engine light is on, check your codes. The code may shed some light.

My cobra did that with the 'b' cam before it was tuned with a custom chip. But my check engine light never came on. It would just surge at idle and would not idle at all with the a/c on.

Disney Lincoln · 06-20-2005, 10:19 PM

If you haev messed with the idle set screw, then the TPS voltage is off. But that's not the issue right now.

Do this.....
Unhook the battery for a minute and step on the brake pedal to discharge voltage.
Get the car to operating temperature. Then unhook the connector from the IAB. Start the car. If the car doesnt want to idle, turn in the idle set screw until it does idle. Then you can set the TPS, set idle this way to about 800 rpm. If you haev to turn the set screw in more than TWO full turns from fully closed, then remove the TB and drill a small hole in the blade and start over. Once you haev it idling with the IAB unhooked, then you can set the TPS to .99 volts and make sure everything is good. Then you can reconnect the IAB and all will be well with the idle.

If it still acts stupd. You should try rotating the MAF meter 90* at a time until it improves.

Pull codes for the CEL. Fix any problems with that before you try to fix anything else.

Set base timing to 10* and FP to 39psi.

Adjust those at the track or on a dyno.

93Cobra#2771 · 06-21-2005, 09:32 AM

My first vote - clean the sensing wires on your MAF. I suspect they may be oil contaminated. Clean them with CRC electrical contact cleaner (no touching) until they are nice and shiney.

coupe · 06-21-2005, 11:29 AM

First...It's not the cam.

Second: YES!!! You need to get your coolant temp sensor hooked back up. The computer NEEDS this for operations at cold-startup. Even if you want to run an aftermarket; hook it up.

93Cobra#2771 · 06-21-2005, 11:33 AM

Quote:

Without the ECT your engine may be running in open loop constantly which may be the reason for the problems.

Running without the ECT will not cause you to run open loop - it will give you a check engine light, but you will still go into closed loop...

On fox bodies, anyway. I assume he is a fox body by his avatar...

Italian LX · 06-21-2005, 11:55 AM

Quote:

Originally Posted by 93Cobra#2771

Running without the ECT will not cause you to run open loop - it will give you a check engine light, but you will still go into closed loop...

On fox bodies, anyway. I assume he is a fox body by his avatar...

OL start-up is a function of time; not ECT.

06-20-2005, 05:51 PM	#1
ujslost Senior Member Join Date: May 2005 Location: ALBERTVILLE, AL Posts: 498	surging? Ok guys got the motor in finally, been driving it around last 2 days, trying to get the computer to learn its stuff again. Well Its got a problem that pisses me off, heres what we got here. timing is on 15-16 degrees btc trickflow stage 1 camshaft when i crank my car it acts like its carbed, wont run hardly, after i drive it a min or so its ok, whats pissin me off is this after its warmed up and i stop at a light, it idles high for a min or so, then sometimes it idels down and sometimes it doesnt. I can come home cut it off, let it sit 5 mins, crank it and it idles around 1200 rmp or so, drive it stop let it idle, idles at almost 1500 rpms. I have tried to idle it down with the idle screw, but at 900 rmps it sounds like its about to die, (possibly just sounds this way because the cam is loping harder at a low rpm) basically i want it to idle right, this idleing high and the low pisses me off, i want to hear the cam when im sitting still, and with it idleing high i cant and it sounds like crap. I havent checked the TPS yet didnt think i should since, i didnt remove it from the throttle body. I had this problem last time i put heads and crap on, i cant remember for the love of god what i done to fix it Friggin check engine light is on also, could it be because i removed the factory temp sensor, and installed a mechanical temp guage?

06-20-2005, 07:04 PM	#3
ujslost Senior Member Join Date: May 2005 Location: ALBERTVILLE, AL Posts: 498	Re: surging? nope not the ECC coolant, i changed the correct one, the one beside fuel injector driver side, all the other crap is plugged up

06-20-2005, 10:19 PM	#6
Disney Lincoln Senior Member Join Date: May 2005 Posts: 290	Re: surging? If you haev messed with the idle set screw, then the TPS voltage is off. But that's not the issue right now. Do this..... Unhook the battery for a minute and step on the brake pedal to discharge voltage. Get the car to operating temperature. Then unhook the connector from the IAB. Start the car. If the car doesnt want to idle, turn in the idle set screw until it does idle. Then you can set the TPS, set idle this way to about 800 rpm. If you haev to turn the set screw in more than TWO full turns from fully closed, then remove the TB and drill a small hole in the blade and start over. Once you haev it idling with the IAB unhooked, then you can set the TPS to .99 volts and make sure everything is good. Then you can reconnect the IAB and all will be well with the idle. If it still acts stupd. You should try rotating the MAF meter 90* at a time until it improves. Pull codes for the CEL. Fix any problems with that before you try to fix anything else. Set base timing to 10* and FP to 39psi. Adjust those at the track or on a dyno.

06-21-2005, 09:32 AM	#7
93Cobra#2771 The Kocky One Join Date: Dec 2004 Location: Yeah, but those cutters won't bust any walnuts.â„¢ Posts: 1,948	Re: surging? My first vote - clean the sensing wires on your MAF. I suspect they may be oil contaminated. Clean them with CRC electrical contact cleaner (no touching) until they are nice and shiney. __________________ *For Sale: Reproduction Window Stickers, 87+ Mustangs, Cobras, Lightnings, and HD F150!* Richard White 93 Cobra Kocky will be back!

06-21-2005, 11:29 AM	#8
coupe Super Moderator Join Date: Dec 2004 Posts: 6,313	Re: surging? First...It's not the cam. Second: YES!!! You need to get your coolant temp sensor hooked back up. The computer NEEDS this for operations at cold-startup. Even if you want to run an aftermarket; hook it up. __________________ " If you can't explain it simply, you don't understand it well enough. " - Albert Einstein