Missing/Vibration when hot

[mitchell27]

Hey guys, wondering if anyone can help me with an ongoing issue I am having with my 95' TS SE 4cly EFI.

When the engine bay heats up, I am getting large amounts of vibration and a loss of power which I (in my limited knowledge) believe is the engine missing.
Relevant info:
-Checked spark plugs, all looked exactly the same, so I do not believe it is a problem related to one cylinder
-It is definitely when the engine bay heats up, not the engine itself. For instance, if I drive around town, then onto the hwy, I get a huge amount of vibration. But if I get straight onto a hwy the vibration is no-where near as bad (even though engine temp sits on half the whole time in both scenarios).
-I have noticed that the problem is reduced when I installed a new distributor cap, so I am thinking that I am getting a weak spark to distributor after the engine bay heats up?
-New spark plugs, spark plug wires, distributor cap. Didn't replace distributor rotor as it looked fine (compared it to a new one).
-I have unplugged and cleaned connectors around distributor & ignition coil (sanded terminals and sprayed with Mass Air sensor cleaner).
-It has an aftermarket Bosch ignition coil.

Thought I'd ask the community to see if the issue can be narrowed down, as I am a little stumped at this stage.

EDIT, forgot to add:
I also believe the ISC is faulty: Revs do not remain steady when I turn on A/C, lights etc, instead they just drop. I am also getting a small stutter/surging when idling after the car has warmed up. So I am unsure if this is contributing to the issue. I have cleaned the TB, ESC etc. No change in vibration seen at all.

[magna buff]

vibration/miss/ loss of power

check
engine and gearbox mounts -- front and rear
the CV boots and CV joints


stutter and loss of power
is the engine check light on ?
if not u will have to track down faults that do not throw a code

in the dark pop the bonnet and run the engine see if there is an arc or sparkles

isc costs a lot to replace

to test undo it from the throttle body keep its wires connected
if it retracts as you start the motor it is working correctly

TPS faulty
02 sensor
fuel filter
maf (has four functions ) cleaning wont help if it is faulty

air filter, coil exciter ,knock sensor
..if you do have doubts about the coil replace it

the wires and 4 pins connector into the distributor, can have broken or bent pins to wires ,corrosion

[mitchell27]

Thanks for the reply!

I just checked the ignition coil when it was hot with a multimeter, and I think it might be the issue. the primary resistance was 1.7 where manual states it should be 0.72-0.88. secondary circuit had no resistance at all, which I think means its buggered.
Rang around the auto stores and no-one has one in stock, so i'll post an update in a few days after I get a new one fitted (going to get an original, since this aftermarket one only last a couple of years).
I admit I didn't think it would be a coil, as I've had one go and the car behaved completely differently (just shut down on road and wouldn't start again until it had cooled completely).

Had a mechanic friend look over all the mounts and CV joints (ended up replacing the L side). Couldn't see any sparks at night (tested this a while ago when researching the issue).
Distributor etc. all in good condition.
Might have to look at getting a new TPS so solve the idle issue.

Thanks again for the help, fingers crossed a new ignition coil will be an easy solution to the problem!

[MadMax]

Rang around the auto stores and no-one has one in stock, so i'll post an update in a few days after I get a new one fitted (going to get an original, since this aftermarket one only last a couple of years).

Been there, done that.
A new coil dies after a short life because the voltage transistor is out of spec, and overloading the coil. (my interpretation).

Solution: Wreckers, grab both coil and power transistor.

[mitchell27]

I've already bought a coil online, but I'll take your advice and get down to the wreckers and grab a transistor as well, as that could be another issue (I keep the spark plugs/leads/dizzy in good condition, which is apparently another cause of the coil failing early).

Thanks for the help, crazy that there is still a good community here for such old cars!!

[mitchell27]

Update:

No change after replacing coil exciter/ignition module and ignition coil. I am confident all leads, distributor etc. from ignition coil to cylinders are in good condition. So I think I can now rule out ignition issues being the problem.

So moving onto Magna buffs other recommendations, I'm thinking it must be related to moving parts. I've attached a picture of the engine mount located right near the radiator, as it looks buggered and off-centre (thoughts?). Otherwise, all other mounts look and feel fine.

No CV knocking/grinder etc. noises when turning, however the inner CV joint boot looks pretty old and the clasp doesn't look tight. So I'm thinking it could also be an issue? I'm not really sure how a fault inner CV would behave...

Further information on the issue (in the hope it helps), the vibration starts immediately after the engine is begins to accelerate the car. ie (I have a manual), if car is in gear clutch out, if I let off the accelerator slightly and the engine is coasting, zero vibration. The moment the car begins applying force through the shaft to accelerate, big amounts of vibration. (I've been listening for any clunks or anything when alternating between coasting and accelerating and I cannot hear anything).
It is still influenced by ambient temperature, we just had a cold snap down in melbourne and it feels almost fine now, until it heats up.

The other thing I read about in the manual was the 'roll stopper', but I can't work out where it is!! picture in the manual isn't really helping me. should I be concerned with this?

[MadMax]

Compression test is next.
So is checking for air leaks.
Check drive shafts for axial play.

Manual gearbox TS doesn't have a roll stopper. Engine mount looks ok.

[mitchell27]

Thanks for the reply MadMax, I'll have to source a compression test kit before I can test the cylinders.
I can't hear any typical vacuum leak noise, have had my head under the bonnet and accelerated the engine to listen. I know that might not be such a great test, but I'm not sure how to test it further than that...

Drive shaft play seems to fit well. the whole LH shaft was recently replaced, so I might just replace the RH side as well if I'm unsure about that inner CV joint, and see how everything looks/feels when I'm pulling it out.

Just have to find the time !

Thanks again for the help, appreciate it a lot!