Running on 4 cylinders?

[mjernigan]

Hello all,

:1zhelp:

I need some help. My car started missing pretty bad after I got on it for a few seconds yesterday.

The car seems to be running on 4 cylinders.

I have checked all of the spark plugs and each plug does get spark from the coil pack.

However, If i unplug the fuel injector wires to Both Cylinders 5 and 6.

Firewall
6
5
4
3
2
1
Front of car

The cars Bad idle does not change. If i unplug the coil wires to plugs 5 and 6... the cars bad idle does not change.

The idle does get worse if i unplug wires from 1-4.

Also, I have also swapped out the injector pack with an extra one I have laying around... and that did not change the bad idle.


Any suggestions on what to check next?


Thanks,
Michael

 

[rayall01]

Hate to be the bearer of bad tidings, but, 5 and 6 are usually where the head gasket blows. The same thing happened to me when mine went.

 

[mjernigan]

Hate to be the bearer of bad tidings, but, 5 and 6 are usually where the head gasket blows. The same thing happened to me when mine went.

Thanks for the quick response..

Could be a BHG (would be the second one)... but, I find it strange that with no spark / no fuel in one or both of the cycinders that there is no difference with idle or even if i give it some gas.

The head gasket is not too old...and was installed with ARP studs and retorqued.

I will try a leak down test this weekend... however... I would like to troubleshoot all items till then.

Thanks again..

 

[hvyman]

a bhg is not going to give a mis fire. ohm out the injectors. pull the plugs and ground them and see if you are getting spark them.

 

[rayall01]

a bhg is not going to give a mis fire. ohm out the injectors. pull the plugs and ground them and see if you are getting spark them.

Ahem, read the post. He says that he has spark going to all six cylinders. If there's enough coolant getting into the cylinders, it won't fire. That is why pulling the plug wire, or injector wire will not change anything. As I said, it happened to me. Blown head gasket, same exact symptoms. Ran like it was misfiring, and pulling the plug wires did nothing. That's why I told him what I told him. It may not be, and I hope it's not, but you can't overlook the possibility. Also, it happened after a boost run, and that's how mine went. Too much alike to overlook.

 

[mjernigan]

a bhg is not going to give a mis fire. ohm out the injectors. pull the plugs and ground them and see if you are getting spark them.

Ohm on 5 and 6 were at 3.5ohms... so in spec.

Dropped in two new plugs after checking they had spark from wire... nada.


As for the BH post... not ruling it out by any means.... but just checking all other ideas.

 

[adampecush]

check the spark plug valley for oil/water. If it is full, the plug wires will arc, not firing the plugs on these cylinders. Clean/dry them out and report back to us.

 

[mjernigan]

check the spark plug valley for oil/water. If it is full, the plug wires will arc, not firing the plugs on these cylinders. Clean/dry them out and report back to us.

When i pulled the plugs to replace them.. I checked to make sure they didn't have oily water down there.

I had the old oil/water in the spark plug holes.. back when had my MR2 Turbo - rain water always landed on the top of the engine.

http://www.thejernigans.com/mr2/

Thanks for the advice though..

 

[rayall01]

Ohm on 5 and 6 were at 3.5ohms... so in spec.

Dropped in two new plugs after checking they had spark from wire... nada.


As for the BH post... not ruling it out by any means.... but just checking all other ideas.

As you should. Always explore all possibilities, that way you'll be sure. I was mostly just yelling at hvyman.:icon_bigg

 

[mjernigan]

So far no luck...

Well.. I'm off to dinner.. I'll check back to see if anyone else has something else for me to check out.


Thanks for the help so far.

 

[3p141592654]

MIL light on? Check ECU for codes?

 

[Another MkIII]

Do a compression test. If you have low/no compression on 5 and 6, you may have a BHG (mos likely). But in any case, you will be tearing the engine down at least partially if it fails a compresion test.
-AM3

 

[mjernigan]

Cylinders 1-4 between 150-180...

Cylinders 5 and 6..... around 60...


bhg between 5 / 6.

Well.. this just speeds up my current project of taking my motor out of a 87 body and putting it into the 89 body thats in my driveway.



Thanks all.