1999Transamman

iTrader: (18)

Okay so for the last couple weeks i've been trying to figure out what is going on with my T/A. Its not firing on cylinders 7 and 8, the headers tubes are cold as ice. I swapped injectors, coils, wires, plugs. Its calling out P0357 and P0358 on my scanner. I can smell the gas in the exhaust. I've changed the crank position sensor, but that didnt do anything. I checked the pushrods and valve springs and nothing was broke or bent. Im down to bad compression or something faulty with my ecu. I need some help on this one, not sure where to go or what wires to check specifically. Please help!!!

SSAUTOCHROME

iTrader: (2)

Hope this helps you out man:

P0357=Ignition Coil

http://gearchatter.com/viewtopic8865...e6f8fb735fb8a7

P0358=Iginition Coil

http://gearchatter.com/viewtopic8864...e6f8fb735fb8a7

Your cyl. #7 and #8 coils need to be checked for connection errors (i.e. connection loose or broken). Try connecting back up your stock coils to see if there is an issue with your replacements. I think it is just a bad connection. Check everything from the connection to the coil pack/connection from coil pack to plug wire/connection to spark plug. You could get a spark plug tester to find out if these cylinders are firing at all. I am guessing NOPE!

jimmyblue

iTrader: (11)

#7 and #8 are also the ones most prone to crud
up the injectors. So you may have a lean misfire
problem that just looks like fail-to-spark. If you
have an old-timey timing light with inductive
pickup you can tell whether spark is being thrown.
It's fairly simple to swap the #7 and #8 injectors
with #5 and #6, and see what happens, next.

1999Transamman

iTrader: (18)

Sweet, thanks guys. I'll report back

1999Transamman

iTrader: (18)

Alright, so update. I did put new injectors on, no joy, swapped injectors around, no joy. So after that I pulled the ECU out, and checked all wires for good continuity and they all checked out. I did find that the brown wire which was labeled as pin 60 on the diagram was actually pin 50 I believe, it had good continuity all the way to the connector at the coil. Now before you say the coil is bad, i've swapped coils around with good coils and that didnt fix it. All the pins are straight, and the female ends arent pushed in. Im an avionics tech for the navy so im fairly familiar with checking for faulty wiring ect... So I am convinced the wiring is not the issue here. Could fuel pressure cause this, would 7 and 8 solely be prone to problems with a low fuel pressure? If so, can I just hook up a fuel pressure gauge at the valve on the fuel rail? I have a guy at the dealership who is going to hook me up with a new ECU for 200 but I dont want to keep throwing parts at this. I guess checking to see if the spark plug is sparking. Im just baffled right now with this one.

1999Transamman

iTrader: (18)

Well I reinstalled the ECU, and I could feel the cylinders firing occassionally. The header tubes were warm this time. However there is still a very noticable miss, and the P0357 and 0358 codes are still popping. Im really convinced this is a driver issue within the ECU. I want to take the ECU off of my SS and try it, but if I f'd that one up i'd be up **** creek. Is there any way of knowing for sure its an ECU issue?

jimmyblue

iTrader: (11)

If you have a 'scope you could look at the injector and PCM
ends of the harness, see that (or not) #7, #8 have low side
drive signals that look consistent with the working cylinders
and high side voltage that's a solid +13V (ish, but key is that
it is the same as everybody else).

Maybe a little probing around will at least convince you that
a harness fault, etc. isn't in the mix before you mess with
the expensive & electrically fragile.

jrocstar

iTrader: (31)

just run a compression test just to check and do leak down checking for head gasket failure or cracked block or head. it is simple and can fix alot of pains. is there any knock picked up? i had a friends chunk a piston at idle on his 53k mi ls1 at idle so anything can happen

1999Transamman

iTrader: (18)

Well im going on vacation for the next week. Its not picking up any knock, which is good. Im gonna try the Oscope Jimmyblue, and Jrocstar i'll do a compression check and leak down. I did replace the head gaskets 7k miles ago. It ran great for 7k then started f'n up. I replaced the gaskets with the GM performance gaskets, and torqued the head bolts in sequence to specs. I hope its not those damn things. Id rather pay the couple hundred for a computer than pull those damn heads off. Ahhh my car is like a big freakin model, all pretty and **** but useless for anything else....

thunderstruck507

iTrader: (18)

I'm having the same type problem but the problem follows the coil packs, so I know it's not head gasket or pushrod or valve ect

this blows

joecar

Follows the coil packs when you move the coil packs only...?

Then you need to replace the coil packs.

thunderstruck507

iTrader: (18)

turns out it was the coil pack harness

swapped a set from a 5.3 and it fired right off

1999Transamman

iTrader: (18)

Im sure its not my harness, i read off all the wires with the multimeter and nothing seemed out of place.

thunderstruck507

iTrader: (18)

Cool, just an idea. I couldn't find anything wrong with mine, but the fact it followed the coils led me to believe the problem was somewhere between the engine harness and the plug wire, and since replacing coils didn't help the coil pack harness was the next logical thing.

I'm gonna strip it eventually and find the problem so I have and extra set of coils if I need them.

blown03mustang

im having the same problem, i cant figure it out. i checked each header primary and they were all hot. it sounds like mine is runnin on 6 cyl. OP when u figure it out let me know cuz im stumped

maybe my car just doesnt like me

Dan Stewart

Still doesn't mean that the wiring isn't faulty. With enough time, you will find out that just because you show continuity when you test it, doesn't mean that the wire holds continuity when under usage. Also, the meter will still show the same resistance between both ends of the wire, even if it is shorting to ground between the both points. Because the resistance between the two points hasn't changed. Make sure you check everything to ground, also, if you haven't already done so.

Follow Jimmyblue's and jrocstar's advice to the tee, first, then go from there.

1999Transamman

iTrader: (18)

Well I did like everyone recommended and everything checked good. So I bucked up and bought a new PCM from a member on here, tuned and all. I plugged it in and the car ran smooth as silk, so all I can figure is the drivers for #7 & 8 were weak. Thanks for the help everyone.