Slow Start & Rough Idle. No Clue!?

[travs_dsm]

1997 Eclipse GSX Automatic
67,000 miles
100% Stock no mods

Parts replaced so far:

Coolant Temp Sensor
Gas Cap
Plug Wires
New battery

Tests done so far:

Tested ISC, got 33ish Ohms across all leads

Background:

The car was overheated (busted turbo coolant hose) and required a new head/head gasket. I'm not sure if the car was hard to start before as it did not have but 14psi across all cylinders when i got it.

So the car takes forever to crank when cold, although me giving it gas via the pedal seems to help it finally start. It will never start if I just turn the ignition without pressing the gas. Once the car cranks, it has a rough idle: 750RPM in Neutral all accessories off per spec. In gear it drops down to like 400RPM and the idle of course gets very rough. I am not getting any CEL and there are no codes in stored.

The car runs great other than the rough idle and slow start. Also when I am cranking it for a while I can smell a ton of fuel which led me to replace the Coolant Temp Sensor just in case, but it made no difference. Another possible clue is that warm starts are much easier than cold.

I have replaced the battery (800CCA), NGK plug wires, CTS and even the gas cap. I was sure it was the ISC, but it tested out good with the multimeter.

I'm at a loss and I don't know what else it could be. I'd appreciate any help offered in tracking this down! Once I get it running 100% I'll post some pics of this thing, it is gorgeous! Thank you!

 

[dsmlover07]

Check fuel pump, injector wiring, and a bad battery.

 

[Diamond Star Werks]

BTW, be careful when you remove your fuel rail that the little plastic standoffs don't fall off. Two of mine did and of course fell down through the holes in the intake manifold to the back of the motor. I had to go buy a flexible claw device to retrieve them! I was cursing like a sailor !

Thanks everyone for your help in my thread! I really appreciate it! [/QUOTE]

haha Yeah i got tired of dropping mine down throw the intake so I took some ultra grey to the bottom of them. Ha no worries about dropping them now

Also with the starting problem just because your IAC/ISC (whatever you like to call it) tests good doesn't mean it necessarily is. I have had a maxima in the shop that everything tested good on it but I could never get the idle to change. I have a snap-on verus scanner which allows changing of the IAC %. After removing it I hooked the scanner back up and watch the IAC as I changed the values and it would try to move but the motor was simply stuck. So it could be be stuck closed which would explain why pressing the gas would help it to start as it would add extra air that was needed. Also try using starting fluid alil squirt and if it starts right up and cuts off or stumbles around and cuts off you may have a fuel pressure problem. Another possiblity could be during it overheating the crank or cam sensor got damaged. If they are bad then you wouldn't normally get a CEL. You can back probe them on the signal wires and rotate the engine till the metal plate slides over the sensor tab. Then it should read approx. 5V give or take .2-3. And voltage should drop to an approx. 0 when the plate moves away from the sensor tabs. Hope this helps you fix your car!

 

[travs_dsm]

haha Yeah i got tired of dropping mine down throw the intake so I took some ultra grey to the bottom of them. Ha no worries about dropping them now

Also with the starting problem just because your IAC/ISC (whatever you like to call it) tests good doesn't mean it necessarily is. I have had a maxima in the shop that everything tested good on it but I could never get the idle to change. I have a snap-on verus scanner which allows changing of the IAC %. After removing it I hooked the scanner back up and watch the IAC as I changed the values and it would try to move but the motor was simply stuck. So it could be be stuck closed which would explain why pressing the gas would help it to start as it would add extra air that was needed. Also try using starting fluid alil squirt and if it starts right up and cuts off or stumbles around and cuts off you may have a fuel pressure problem. Another possiblity could be during it overheating the crank or cam sensor got damaged. If they are bad then you wouldn't normally get a CEL. You can back probe them on the signal wires and rotate the engine till the metal plate slides over the sensor tab. Then it should read approx. 5V give or take .2-3. And voltage should drop to an approx. 0 when the plate moves away from the sensor tabs. Hope this helps you fix your car!

Thank you for your post as it made me think back to when the CEL originally came on with P0505 (IAC/ISC fault). I went as far as testing the IAC/ISC with my multimeter and it tested within spec across the coils, so I thought it was good to go. Since I am working solo, I went with your suggestion along with the original CEL code and ordered a replacement IAC/ISC from Advance. I am pleased to report that the new part fixed the issue!

Lessons Learned:

1.) follow up in detail on the original CEL, the computer most likely knows more than I do

2.) just because a part tests out good resistance wise doesn't mean it is working correctly.

3.) The IAC/ISC that Advance Auto sells as brand name BWD is actually stamped Mitsubishi on the actual part. $80!

Again, thank you to everyone who lent their time and attention in helping me track this problem down. You guys saved me from taking it to the dealer and getting robbed! At least now I have a backup coil, a brand new CTS and new plugs/wires!