No.1 Cylinder Issues....need help/advice

[satx88supra]

Heys guys I need some help/advice on what to do with my car. Here's my issue and a little bio on the car...

year - 1988 7MGTE
engine - rebuilt (if you need spec let me know)
Miles - driven about 1100 mile so far

Background on issue....
My car developed a miss a while back but i felt i would fix it later due to having other issues to deal with. The car has always had a high idle (1100-1300rpm) due to my improper set up of the CPS. Car was zeroed out....just that when I installed the CPS I didn't leave myself alot of adjustment to back it down. Well today I decided to adjust the CPS and try to get it to spec idle range then properly time it. So when I got it setup and adjusted (idling around 750-850rpm) the 'miss' i felt at high idle was more pronounced that I could tell something is wrong. I started pulling the spark plugs from the coil pack to see if i could find the issue. Idle changed, for the worse, on every pull except No.1 cylinder.....no change....uhh ohh! I then pulled the wire from the spark plug and it was firing to the spark plug. I swapped spark plugs with number six to veriy it wasn't the spark plug. Same issue same cylinder so spark plug is ok.


So now I'm asking for help on what to do next.
Things I've done or planning to do. Would appreciate if anyone thinks i'm on the right tack or other suggestions.

1) removed spark plug to find and oily 'gunk' on cylinder. Used a screwdriver to lightly remove some off the top.
2) Will check resistance on the injector
3) Will use the online TRSM to check at ECU and resistor

Also on another note. If I done happen to get a fire in No.1 cylinder would the oily debris the cylinder be harmful? I really don't want to remove the head but i'll wait to hear what any of you have to say. It's late and i'll try and remember to take a picture of the 'gunk' in the morning.

 

[Smashey]

most likely have a dud injector. pull the 1st injector wire and if it runs same as before get a new injector.

 

[satx88supra]

I believe i did that and was leaning towards a bad fuel injector. I redo that test in the morning to verify.

 

[satx88supra]

OK. So I ohmed the injector and its within specs. I also checked the voltage at the B+ resistor and thats fine. I can still have a bad injector even if it ohms out correctly...right? Just want verification.

 

[satx88supra]

Ok i have done a little trouble shooting this afternoon and now im stuck as what to do again. Here's what I've done...
1. I checked voltage at the B+ resistor....that was fine
2. Rechecked spark from coil to plug
3. Ohm out all injectors
4. Swapped No.1 cylinder injector with No.2 cylinder injector

Car still had miss but its still on No.1 cylinder. So i believe that confirms an electrical issue to the injector. So can anyone help me on trouble shooting or fixing that issue.

 

[jake8790]

Compression test.

 

[Maple191]

Compression test.

^^^^ This.

 

[satx88supra]

ok I'll check that to make sure i have compression.

 

[hvyman]

When it was rebuilt what head gasket was used?

 

[satx88supra]

When it was rebuilt what head gasket was used?

2mm HKS metal headgasket

Ok I did the compression test thinking that couldn't be the issue.....

No.1 = 65
No.2 = 150
No.3 = 148
No.4 = 148
No.5 = 148
No.6 = 150

WTF MAN!!! So i guess i'm heading towards pulling the head! I guess i'll search first on how to diagnose a valve issue before I do that. This sucks......7M.....you love or hate them!! But I'm going to chalk it up to user inexperience for now buuut this is gettin close to hating 7m's. If any of you got instructions on diagnosis of low compression let me know. This sucks!

 

[hvyman]

Was the block machined?
Was the rear timing cover machined with the block?
Any rivets touching the sealing surface?

 

[satx88supra]

The block was machined and the head and cover was also. I guess i didn't want it to be a compression issue because a spent so much time trying to get the HG situation taken care of. A few other Supra guys in my area are suggesting bent valve issues. So I'm going to try and get my hands on a leak down tester. I really hope its not a gasket issue but either way it looks as if i may be pulling the head.

Another question.....Can valve clearance issues cause this? Or worn springs? Just wondering because while i wait on a tester i was going to check clearances. I need to start taking more time with this car...it's very unforgiving.

 

[jake8790]

Broken ring land

 

[adampecush]

broken ringland should show more compression than that, mine still made 125 psi and the ringland was broken over 1/8 of the piston. Start with measuring valve clearances and go from there.

 

[jake8790]

I had broken rings and 60 psi

 

[satx88supra]

Ok... after calming down I went back out and poured a little oil down in No.1 cylinder. Compression test did not change ....65psi. I guess that can rule out rings huh. I'm going to check valve clearances next. I'm would rather it be a valve issue because if its hg i'm going to be upset. My biggest fear is lower end. Hopefully the oil test will keep from the bottom end.

 

[hvyman]

Leak down test will tell you if it's a valve ring or hg.

Might e able to rent one from autozone or kragen.

 

[grizlbr]

Check the valve lash. Has had miss since rebuild? Have to pull valve cover to pull head any way. No tight followers use air adapter in spark plug hole to check valve seats for leaks @ TDC on compression stroke. Adapter should have instructions: READ & FOLLOW!

 

[Supracentral]

Check the valve lash.... No tight followers

Supra motors don't have valve lash, they use shims. There are no "adjustments", you have to replace the shims if they are out of spec. Also, they don't have followers (rocker arms), they are a DOHC design that has the cam lobes riding directly on the shim buckets that are directly on the valves...



Please don't give small block chevy advice for a Supra. It just causes confusion.

 

[satx88supra]

Thanks supracentral ...yeah i was a little confused but looked it up and you confirmed. I ran out of time today but i did get the valve covers off. Rotated the cams to check clearances. Using my 0.15mm feeler gauge couldn't slide through the cam and shim on the intake side. Using the 0.20mm gauge on the exhaust side didn't go through either. And it's tight.....i even went to a 0.063mm feeler and it didn't slide through. So i guess I'm learning how to set clearances. I had a buddy help adjust them a while back. So hopefully when i get some time i'll set the clearances. If being off that far and me driving the car like that do i have a chance of burning up any valves?