Toyota Celica Supra Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
2,741 Posts
Discussion Starter · #1 ·
when i first start my car in the morning, it runs rough. the colder it is the rougher it runs. the idle will fluctuate between 500rpm and 1500rpm. if i hold the throttle at 2k rpm for a minute or so, this usually solves the problem and the car will drive fine and idle nicely. if i start the car when its warm, its a little rough as well, but a quick rev or two usually solves that. ive cleaned my throttle body, egr, and idle contol valve. the motor has been seafoamed and the intake manifold is pretty clean. i tested the resistance of the icv and it checked out fine, but i forgot to test it on a battery. i dont think thats my problem since it idles fine after its run for a minute for so. im not sure how to test my tps, but i dont think thats the problem either since it does it with or without the tps plugged in. the only thing else i can think of, is that my cold start injector is not functioning properly, either putting in too much or not enough fuel when i first start it up. before i go and replace it, i just want to double check that my symptoms are in fact pointing to my cold start injector. thanks.
 

·
Registered
Joined
·
2,121 Posts
i think ive got a cold start injector problem as well. its hard to diagnose the symptoms so ill subscribe to this thread to see what peeps say....
 

·
Registered
Joined
·
125 Posts
pull the connector for the cold start injector time switch to see what happens. i have started a car with out it just takes a couple more seconds of the starter turning.
 

·
Registered
Joined
·
2,800 Posts
if i start the car when its warm, its a little rough as well, but a quick rev or two usually solves that. (normal operation due to airtemp sensor heat soak. computer thinks intake air is hot and doesn't supply enough gas until sensor cools to correct temp)

take a look at the online tsrm for tests for your problem. iirc, engine usually stalls or runs rough when csi doesn't supply enough gas. 500 could be stall condition while computer tries to go to 1500 for cold startup engine.
 

·
Registered
Joined
·
2,741 Posts
Discussion Starter · #5 ·
if i start the car when its warm, its a little rough as well, but a quick rev or two usually solves that. (normal operation due to airtemp sensor heat soak. computer thinks intake air is hot and doesn't supply enough gas until sensor cools to correct temp)

take a look at the online tsrm for tests for your problem. iirc, engine usually stalls or runs rough when csi doesn't supply enough gas. 500 could be stall condition while computer tries to go to 1500 for cold startup engine.
well, sometimes if i dont touch the gas pedal it will stall out. if i leave it be, the idle will fluctuate at first then the rpms will go to 500 and run really rough, almost like its got a really nasty cam in it, lol. it will eventually balance out on its own and hold a nice idle. i just hold the gas at 2k rpms for about a minute because its faster that way.
 

·
Registered
Joined
·
429 Posts
When I first got my MKII (from my cousin, the original owner) it had a very hard time starting when hot and was cold-blooded for a FI car when starting from cold (minimum 0C because it's not used in winter). He'd taken the car to a number of mechanics, without success and it was driving him nuts.

I didn't know anything about the MKII at the time so started troubleshooting with the shop manual. After much checking, I decided that it had to be a fuel problem - but what?

I mounted a fuel pressure gauge and watched for the leakdown. Sure enough the pressure dropped way too fast so something was leaking. I pulled off the TB, then the upper plenum - to get to the cold-start injector and could see right in the plenum, the telltale stain from dribbling fuel. I disconnected the cold-start injector and the hot hard start problem was solved.

I've not had a cold start injector since and don't miss it. The slight cold-blooded start is not an issue and since it is a bad idea to rev a cold engine anyway, nothing is lost. Of course, this car is not used in winter so for those that need to start from sub-zero temps, removal may not be an option.

As a bonus, the opening for the cold-start injector fuel line was a perfect spot to screw in the FP gauge.

Hope this helps,
Damian

 

·
Registered
Joined
·
15 Posts
Cold Start Issue

I have had a similar problem until today.
I wnet looking for the timer switch that controls the cold start injector only to find the air control valve needed freeing up with WD40.
My engine is the 5ME and the control valve is above the intake manifold opposite spark plug 2.
After reassembly the car started instantly from cold and idled smoothly as new.
 

·
Registered
Joined
·
2,741 Posts
Discussion Starter · #8 ·
if i unplug my cold start injector, and leave the fuel line connected, will my problem go away? i just want to double check that it is my problem before i replace it and i want to make sure that its as simple as unplugging an electrical connector.
 

·
Registered
Joined
·
888 Posts
i have disconect my cold start injector too and it run every day with no problems but t° are maybe different in france
i prefer because with the cold start injector my car have an iddle to hight and was too long for nothing to warm , at the cost of unledead!!
 

·
Registered
Joined
·
429 Posts
What I found with mine was that unplugging the electrical connection from the injector made no difference because in my case (your's may be different) the actual injector was leaking under pressure. Not a massive leak but enough that it would drop the fuel pressure down to zero in a short while....then the hard start because of all the extra fuel in the plenum/runners. That was not good for the cylinders either.

The way I originally connected my FP gauge was following Wes H's excellent guide on his website. That's how I found the problem. Without the FP gauge, it would have taken longer. Having one installed in your car can help with diagnosing a lot of other issues too.

Good luck,
Damian
 

·
Registered
Joined
·
1 Posts
when i first start my car in the morning, it runs rough. the colder it is the rougher it runs. the idle will fluctuate between 500rpm and 1500rpm. if i hold the throttle at 2k rpm for a minute or so, this usually solves the problem and the car will drive fine and idle nicely. if i start the car when its warm, its a little rough as well, but a quick rev or two usually solves that. ive cleaned my throttle body, egr, and idle contol valve. the motor has been seafoamed and the intake manifold is pretty clean. i tested the resistance of the icv and it checked out fine, but i forgot to test it on a battery. i dont think thats my problem since it idles fine after its run for a minute for so. im not sure how to test my tps, but i dont think thats the problem either since it does it with or without the tps plugged in. the only thing else i can think of, is that my cold start injector is not functioning properly, either putting in too much or not enough fuel when i first start it up. before i go and replace it, i just want to double check that my symptoms are in fact pointing to my cold start injector. thanks.
I had the same problem. 1987 supra AT N/A. First start up. Would not stay running. I had to hold the throttle down and have it idle above 2000. After about 2 minutes it would magically smooth out. So i took the two bolts that holds the cold start injector and pulled it out. It was covered in soot/carbon. I used a wire brush and some brake cleaner on it and cleaned it up. I also sprayed some down in the hole. I put it back together and it started right up. Before i fixed it it ran rough and acted like it was running on 3-4 cylinders. The whole motor shook and it was horrible. Now it is back to smooth running. So try that first. I had already checked vacuum hoses and wires off.
 

·
Registered
Joined
·
2,139 Posts
a bad or improperly adjusted TPS can give low idle /stall issues as well, really easy to check, just unplug it...
 

·
Registered
Joined
·
162 Posts
While you've got TPS disconnected, measure and test it. Then compare your numbers with standards in manual.

You'll find an interesting surprise here... ;)
 
1 - 13 of 13 Posts
Top