AReynolds91

Ok, so when i start my car on a cold start It idles at like....500ish. It will idle like that until i drive it for a minute. Once I go and drive, it will idle at 1050-1100ish. and be steady. I thought it was supposed to be the other way around? lol

The idle on my ECU is set at 700. and the car never idles at that.

people have told me IACV, just looking for a second opinion.

I dont have heat either, well i do, but i cant have my heat running for the car to get to temp, and i have to be sitting. If the car reaches temp, then i drive, the temp guage dive bombs back to cold. or if i turn on my heat, its the same thing. Car will still blow heat, but barely.

im thinking thermostat... just want a second opinion, because my buddies gsr does the same thing(not the idle issue, just heat), hes replaced his thermostat, and coolant temp sensor.

el crapitan

i'm going to assume from your sig that your car is a 96-up. if that's correct, you don't have a fitv, so that cancels it out as the issue for rough cold start. that system was replaced with a system by which the pcm takes readings from the coolant temp sensor (that's sensor, not sending unit) iat, and possibly eot to determine fast idle or cold start idle. first thing you want to do is check the codes. regardless of whether or not the cel is illuminated, a code may be stored. you may have a correlation code or iac code. it will help you further pin point.

next, if no codes are present, clean the iacv. if the idle problem persists, check resistance of the coolant temp sensor. check it with the engine cold first, then hot. see if the readings fall within spec.

for your heat issue, replace the thermostat. replace it with an oem unit.

if your friend replaced his t-stat with a jobber unit, and the temp gauge still drops at cruising speed or decel and takes long to warm up, tell him to replace it with an oem unit.
if his gauge doesn't drop at cruising speed or decel and he's having trouble getting cabin heat, first check that the heater valve isn't stuck, if it operates correctly, with heat on blast and vehicle at operating temp, check the temperature, by feel, of the heater core inlet and outlet hoses. they should be roughly the same temp. if not, try back flushing the heater core

fcm

I would replace the thermostat, [cheap enough] if for no other reason then to eliminate it as a problem, then I would bleed the coolant system and make absolutely sure all the air is out.

You said, "If the car reaches temp, then i drive, the temp gauge dive bombs back to cold", that would indicate either a thermostat stock open or air in the coolant system or both.

No or poor heat is also an indication of either a thermostat stuck open or air in the system, it may also be, as mentioned, a stuck heater valve or restricted, [blocked] heater core.

What ever it is you will need to confirm the thermostat is working properly and the coolant system is free of air before moving on, to eliminate them as the problem. 94

AReynolds91

Well, i did some troubleshooting, while at cold start with motor running, and rough idle, i unplugged the coolant temp sensor, and idle didnt change. i plugged it back in, and unplugged the engine temp sensor (under the dizzy) and no idle change. Made a few calls, and from what a friend told me its supposed to idle up upon unplugging it.

thermostat, and ivac will be replaced/cleaned this weekend when i have time. I checked the codes 100 times, and nothing comes up.

bigpunn421

a stuck closed thermostat gives you idle problems. i know first hand.

if the iac doesnt get circulated coolant from motor it doesnt see the that the car warmed up. so it adjust the idle for wrong conditions.

the iftv could be problem but obd1 integras only.

when you car is warm are both radiator hoses hot? if not its the t stat. does the needle every go to full hot then drop to cold?

AReynolds91

if i let it run and get warm it will warm up to operating temp, but if i take off and drive up the street it dive bombs back to C.

AReynolds91

BTW, for those of you who didnt read my sig. The motor is in a 96 Cx hatchback. and it also has been converted to OBD1, and im using a P28 ecu basemapped with Chrome.

el crapitan

have you checked resistance of the ect sensor? cold. then hot

AReynolds91

Uhh. No. Alot of my sensors are disabled with the ecu. Ill have to ask my buddy who basemapped ot if thats one of them.... I know nothing about how the program works. But ive replaced the thermostat. Heat.... Finally. Runs and idles as it should... Other than cold starts, and now it has an occasional idle surge.. very slight. Going to clean my iacv and go from there.

AReynolds91

Ok....so I thought of something the other day. Since my car isnt using the stock p72 ecu, and running off a p28 OBD1, the Butterflys in the intake manifold arent being used...there just kinda there. Could this be my issue? I plan on hooking them back up eventually, or getting a itr intake mani, one of the 2. But im just wondering if this could be my issue?

el crapitan

were the secondary runners left open? or closed? if they're closed, then no. since they'd be closed at idle anyways.

itr intake won't bolt up

AReynolds91

Idk if they are open or not.... I havent even tried moving the actuator...

although, I did take video of what the car is doing at cold start, and after driving for like 5 minutes. Lmk if you guy want me to post it or not.

el crapitan

couldn't hurt. go ahead and post it

AReynolds91

uploading to youtubes. Ill post links.

virds

I had a problem with my idle before, 1st thing I did was to clean my throttle body and iavc but that wasn't the culprit only to find out that my map sensor has the problem .. Problem fixed.. The last thing to check is the ecu try using other ecu it may also cause idle issue if you are using a programmable one

AReynolds91

but why, when the motor is warm, would it start up and be completley normal?

youll understand what its doing once i post the vids.