Hesitation when Cold and misfiring, but perfectly fine when warm.

[Supraquick]

Hello

I picked up this 87 toyota supra sport top for $500.

It had an issue with missfiring when cold and when warm.

I took it to my uncles shop as he is a mechanic and it turned out there was a few things wrong.

What they tested. Spark on each cable on the distributor side and on the spark plug side.

1: #2 cyl wasn't working and this was due to a vacume leak on the intake manifold. Once they fixed the manifold leak with found through the smoke machine #2 was firing up. They did a compression test and it was good on all cylinders. They put the smoke machine and no other smoke came out of the engine.

2: the EGR cables were connected wrong,
3: idle on throttle body was set wrong so they adjusted it. It was at 1200 RPM the whole time and they lowered it to about 800.
4: throttle cables were wrong so they fixed those too.

5: distributor cap looked good but on the #2 it looked like there was a smear of smoke on the cap side but we couldn't see any caps.

They tested all injectors with their probe and all were working fine.

After they did all this, they were able to get it idling just fine, but said I might need an AFM with housing as the previous owner had messed with the screw that is on the housing.

Any who, the car runs fine on the freeway and while its warm so I left the shop.

A day later the car started to hesitate and missfire a lot until it warmed up. It only runs rough when its cold.

Do you guys know what else it can be??

My coolant light is on but the radiator has enough water and so does the resivoir. The car doesn't give out any codes and check engine light is not on.

Engine: 7mge

Today in the morning it was raining outside and the car was missing really bad. Not sure if the water had anything to do with it but it never was this bad. After about 15min warmup i decided to drive and it would drive fine on the freeway but at stops it would start to missfire again.

Any help is greatly appreciated.

 

[AJ'S 88NA]

Still could have some codes stored even if the cel isn't on.

Check all your grounds. Did they change the plug wires?

Also the only sure way of checking injectors is to have them cleaned and flow tested.

 

[Supraquick]

I didn't see any codes when doing the jumper thing. I checked grounds from where I can see an everything looks connected.

We also though of the injectors but if it was the injectors it would idle bad even when warm right?

Today I started her up, went through the normal misses and hesitations and then after it was warmed up its running just fine.

Seems weird that in the rain it acted like that the whole time and when its dry out it just does it when cold.

Thanks for the tips though.

 

[Supraquick]

Same thing is still happening. I let the car cool off for 4 hours and went back to start it but I disconnected I blieve the cold start injector. Its a sensor on top of the intake manifold runners. I just unclipped it and the car started and didn't miss or anything. I reved it a couple times, RPMS remained high for a bit then slowly went down.
I plugged it back in and it was somewhat fine again but i would hear misses about every 10 seconds.

I will try in the morning to start it with that sensor disconnected again.

I also did the jumper test again and the check engine light just blinked constantly and no codes.

Any other ideas.

 

[AJ'S 88NA]

Could be the CSI is stuck open causing it to run rich, don't know for sure or how much fuel the CSI spits out.

---------- Post added at 08:22 PM ---------- Previous post was at 08:18 PM ----------

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=1

The CSI could be stuck open, don't know for sure how much fuel could be added though causing it to run rough.

 

[Supraquick]

Hey thanks for the response. We found out the Cold start injector was new and replaced by the old owner, he also put in a new 02 sensor.

I tested the sensors and they all turned out good except for the AFM.
Ohms read as follows:
afm
vc-e2=278
vs-e2 =no reading.
tha-e2=2.5

Last night was a long night. My water gauge stopped working my, the oil pressure wasn't working when I bought it and the over flow tank sensor is out.
I fixed the oil pressure switch created new contacts and hooked them back up to the sensors and voila. I still need the over flow tank sensor though.
My heater never worked either.

I went through the car and saw that the vacum line for the heater was disconnected on the passenger side inside the engine bay. A/C and Heat work perfectly now.

I also created a ground from the head to the body as I only saw the connectors but missing wires.

Today While driving to the shop it was idling and driving really bad even when warm. . My uncle had a spare AFM looked the same but the tunnel was smaller so it wouldn't fit the intake hose. I called a few junkyards but no one had it.

While at it we noticed the inside of the intake elbow that connects to the throttle body had duct tape. I was like WTH, it was all on the inside and a little bit on the outside. So I notice sticky element and its was the tape goo. I also noticed the elbow at the end had fallen apart and they just taped it together.We missed this the first time.

So then Since no one had the part, I just used high quality duct tape and drove it to pep boys and bought a silicon coupler and mated it to the elbow after I cut it and made it look flush.

Car is running perfectly fine, no missess every now and then and no crazy idle like it was today.
Since its warm I can't wait to start it in the morning to see its much better.
I still need to buy an AFM though.

I'll keep you guys posted.

P.S thanks for the link. I used it for Troubleshooting my cars sensors and other components. I think that mickey mouse job they did before with the duck tape was really a contributor to the bad idling.

 

[Supraquick]

Issue us fixed. I replaced the afm and when I started the car it was still acting up, so I check the sparkplug wires and I was getting shocked by the cable that comes from the coil.

Turns out there was a crack in the coil and in the distributor cap. The car starts up fine everytime now after replacing both.