4 cylinder V8 Part II

[USMC302]

Gents, let me go over what we've got here.

It's the 88GT in the sig.
We have narrowed it down to the sparkplugs not firing inside cylinders 1,2,6,& 8.
They will fire outside of the cylinder.
There is spark going to the plugs while running.
It will start and idle fine.
New plugs three times.
New wires.
New cap and rotor.
Fuel pressure good.
Noid light test good, so injectors are pulsing.
Ground is doubled and tested good.
New injectors.
Timing set stock
Compression test good in all cylinders.
Pulled codes 22 and 14 not running, no test yet on running..
Tested TFI nodule at auto Zone 4 times, good.

It will not drive much at all of the 4 cylinders, no smoke, no popping. It was an automatic but was swapped to a 5 speed, still has the stock AOD computer in it, pin #30 is taped off. Firing order is correct. This happened when we changed heads and piston rings and then put the motor back in. PLEASE help. thanks everyone!

Shawn

[PKRWUD]

AND, you moved the plug wires to different locations on the cap with no change, ruling out the distributor.

Damn. This is a good one.

The only thing left that it could possibly be, IMHO, is the ECM. If you have a chip installed, try removing it and resetting the ECM. If you don't, all I can suggest is finding someone with a good ECM that you could borrow to see if there is any change. I don't see any other possibility, but I don't feel comfortable enough to tell you to go buy another ECM, either.

Take care,
~Chris

[USMC302]

Well, I have the brand new ECM I just bought for my car after I fried the other one putting it in the GT without taping off the wire. Now that it's taped off, the ECM should be fine right? I will buy a new one and put it in. There isn't anyway to test the ECM is there? Should I buy a 5 speed or auto now for it?

[USMC302]

Now that it's taped off, the ECM should be fine right?

I meant if I put mine in it, it won't be fried again. But I will just buy another one.

[jerrys84]

could'nt a weak coil, cause lack of spark to the plugs when they are under compression??


thought that was a truth, but maybe not..

[USMC302]

Oops, forgot to add that in the first post, we put my MSD coil on it and no change, but keep em coming guys! The stock coil is back in place now.

[LX XLR8R]

when you did your compression test did you have all the spark plugs out..because it could be blown out inbetween cylinders/gasket didnt seat

hmm..you left in the old cam right..you didnt do anything like change the style cam(etc to a older 302 firing order,and you do have the firing order correct)

pin 30 is elec shift/4x4..out of curiosty why is that taped off..ive ran 9ap computers in 5spds b4..

BTW what is it doing..those plugs are going black?i know that truck computers had tendencies to make the #8 plugs black andthen leading to detination leading to holes in pistons..seen that first hand..strange only in that one cylinder

so its still SD also?if ist still an AOD 88 cmoputer then i dont belive there is anykid of retard between shifts from the AOD that would affect anything

just some random thoughts

[USMC302]

when you did your compression test did you have all the spark plugs out..because it could be blown out inbetween cylinders/gasket didnt seat

The spark plugs were out on the side performing the test on, so four were out at a time. Also, the headgasket on the passenger side head did blow on the first attempt to start it, after going through another gasket it was good to go after that..

hmm..you left in the old cam right..you didnt do anything like change the style cam(etc to a older 302 firing order,and you do have the firing order correct)

Yes, the stock cam is in, it ran fine before the head and piston ring swap. The stock firing order was used before and after.

pin 30 is elec shift/4x4..out of curiosty why is that taped off..ive ran 9ap computers in 5spds b4..

PKRWD stated if a 5speed computer was put in the AOD car, even with it being converted to a 5speed, it would ruin the computer. I confirmed this by putting my 5speed ECM from the Coupe into the GT and it went bad instantly. If I stick with an AOD computer, I don't need to cut the wire, if I go with a 5speed, I needed it cut.

BTW what is it doing..those plugs are going black?i know that truck computers had tendencies to make the #8 plugs black andthen leading to detination leading to holes in pistons..seen that first hand..strange only in that one cylinder

It has no power at all when trying to drive, when we looked closer is seemed the injectors were staying open, when we pulled the cylinders that weren't firing they were wet with gas, not firing at all. The others were normal...

so its still SD also?

Huh?!

[PKRWUD]

SD=Speed Density.

If you're going to get another ECM, definately get one for a 5 speed, but don't forget to cut the wire to pin 30 (removing the pin/wire from the connector all together is preferable).

This whole situation just seems fishy. I can't put my finger on it, but it just doesn't make any sense. It "feels" more like an electrical problem, but I'm not aware of any that would cause your symptoms.

Tell you what, since you have a car you can borrow known good parts from, swap the distributor from your other '88, and see if that makes a difference. Moving the wires around on the cap, yet having the same plugs dead tells me the distributor is fine, but you might as well check it anyway, since you can, before spending the money on an ECM.

Ever think about buying a Harley?



Take care,
~Chris

[mustangman65_79]

I don't know if I missed something, but did u change out the distributor yet? I know my Ranger, and I think mustang also have a chip in the distributor. In the ranger, when they went out, it just stopped running. Try what Chris said, swap distributors.

[302crew]

sounds like your valves arent closeing all the way but you said you did a compression test so that cant be it

[USMC302]

OH, Yeah the car is Mass air, in Cali the 88's were mass air for smog, anyway, yeah I will go ahead and swap dist, the only problem is the GT is in texas and I am in Lousy-ana, so it will be next weekend before I can get down there to swap them. Well, maybe I can find a buddy to swap for me. Any chance of ruining his dist or mine known good one with this swap?

Yeah, we thought it could be the valves too, but again like you said, that's why we did the compression test... Anyway, ok, thanks for everything so far.

[LX XLR8R]

Originally posted by 302crew
sounds like your valves arent closeing all the way but you said you did a compression test so that cant be it

302crew you read my mind(ps update your sig )..if the vlaves are too tight it is possible that it casn make compression for a split second then be gone,,are you usung a regular compresion tester or a leakdown style..

302crew says this because a car we did a head swap did what you are saying too a T..the problem was the lifters..no matter what i couldnt shim the roller rockers enuff to get them too work(or now that i think about it it could of been the rollers rockers were way old and could be geting loose)how old are your rockers and what type are they(pedistal rr, stud rr or stock)

what was happening was the car would idle fine but when you wrapped the gas driving it would die down and the plugs were wet in gas..

so my vote goes to its in the valvetrain..too long pushrods,roller rockers too loose internally or bolted on too loose,bad lifters or hey the springs could be shot and are staying open @WOT

[srv1]

USMC, did you ever check for pinched wires when putting on the intake or possible the 2 harness connectors (black and whtie ones) pins pushed out of the plug? i would check there.

you have firing on 4 of the cylinders but not on the other four? sounds like a wiring problem to me. good luck!

[USMC302]

I was using I regular compression tester like the one you buy at AutoZone.

Whe the head gasket blew the first time we purchased a new stock head to replace it, it cam with new springs and valves, we also bought new springs and for the other head and gave it a valve job to match the other head. The rockers are stock and old (88) and so are the pushrods, they were the same pushrods that were working before the head swap. So maybe the head was milled enough to make the pushrods to be too long?! Should i shim all of the rockers? Just the cylinders that are acting up? Intake and exhaust side?

we checked everywhere for pinched wires but didn't find anything, same for vacuum leaks. I will check to see if maybe the pins on the connectors pushed out of the connecter this weekend too.

Yeah, 1,2,6,& 8 aren't firing, which are on both sides of the motor, which made it difficult to narrow down to a head or something specific.


Thank for all of this, I might finally get somewhere.

PS. When the head gasket blew, we had water in all of our oil and lifters and everywhere, we cleaned it all, including the lifters which appeared to still be ok, do you think the water in the oil system damaged the lifters?

[PKRWUD]

What were your compression results, and was the engine warm or cold when you tested it?

[USMC302]

Warm and all around 135 to 155..


HARLEY????!!!!!!!

Hey maybe we could put together a ford harley.

[USMC302]

SO would it be safe to try some shims on 1,2,6, & 8?

[fiveohpatrol]

You should shim only the ones that need to be shimmed. Did you do the correct procedure when installing the rockers? The lifter needs to be setting on the base circle of the cam (valve closed) and after you get to zero lash, then it should torque down between 1/4-3/4 of a turn.

is this the way you did it?

[fiveohpatrol]

Also, if you have another mass air sensor handy, then try swapping it over. Your current one may have been damaged somehow.

good luck