Hey Guys, thanks for all the great leads!

I pulled the cam sensor and the belt is fine as I could see the cam gear spin. Also, after I reconnected the cam sensor I got a fault code (which should happen).

While checking for spark again, #1 cyl is dead while #3 is good. I swapped #1 & #3 on the coil and #1 coil is not firing. I tested the coil between B+ and #1, #2, &#3 terminals, as well as between the high voltage coil terminals. All were within spec. This would lead me to believe that #1 coil is not receiving a signal from the computer. I have not been able to find a test procedure for this - can anyone help?

BTW I also ran an ASD test off the B+ coil terminal and it passed.


Saylor

 

Coil 1 fires cyl 1 & 4. Are both bad? Did you try the "test light" procedure? It is when you use a test light in B+ and test for an inital flash when key placed in "on", then after inital flash put key in start and look for flashing light?

Also look for "spread" contacts on the coil plug.

Coil 1 signal wire (if both 1 & 4 d/n fire) exits the PCM on the same wire...let me know if 4 is also dead. It passes thru bulkhead connector C141 before coil.

Check the ground for the PCM high current devices (rt headlight ground located on the rt front frame rail). If a poor/intermitant ground, car w/n operate.

 

Hi Kurt

I made some jumper leads and was able to swap around the low voltage coil leads. I can make the #2 &#3 leads trigger the #1 coil but #1 lead will not trigger any of the coils. So, power lead for coil #1 (cyl 1 & 4) seems to be the issue.

My next course of action is to test for an open or ground back to the PCM (once I figure out where it's located). Thanks for the info on connector c141 as I'm sure that info will come in handy.

If it's not the wire is the PCM the only culprit left? And, is it possible for a PCM to die on shutdown?

Thanks, as always!

 

Clarification: The ground lead for coil #1 seems to be the issue. Power comes in on the B+ (pin 3) for all 3 coils and the PCM provides a ground pulse for the coil to fire.

Question: When you did the jumper trick, did you get good constant output for coils 2 & 3?

Make sure to inspect the female sockets for "spreading" when checking the wire back. Also inspect the PCM ground I mentioned before.

The location of the PCM is under the air filter (remove air box, it's under it). It has two big 40 pin connectors on it...can't miss it.

C141 is on the right strut tower. There are 5 plugs there. C141 should be the bottom outboard plug.

Pin out is PCM (plug C1) pin 11 --> bulkhead (plug C141) pin 12 --> coil pin 2. The wire should be a black 20 gauge wire in all locations.

Note: Some of the info in the schematics have contradicted each other and have been incomplete. I had to dig a bit to extract this info for you. I'm letting you know because the info I can provide is only as good as the source. I have never had an issue with this book up until now, but I think everything I given you is correct. Unfortunately I can’t tell you which plug is C1 on the PCM. My location drawing refers the two plugs as C173 & C174. I can’t find any linking data to which is C1 or C2.

Lastly as for your PCM questions, I don’t know why, when or how these thing break when they do. As for “if it’s the last thing”; we’ll see later after a review.


Kurt

 

First off, thanks again for all help Kurt!

I tested from the coil plug to the PCM plug and had continuity and therefore didn't test in the middle at the bulkhead. I also tested for a short to ground and all was fine.

Any other possible culprits beside the PCM at this point? And what year/model PCMs interchange with a '98 3.5L Intrepid. For <$50 I might just throw a used one in.

Saylor

 

/QUOTE
Make sure to inspect the female sockets for "spreading" .... "All pins Looked OK but ... Also, if it were the ground I would think all coils would be affected, no? /QUOTE

No, not all. If the pin for coil 1 (cyl 1&4) were bad, then only those cylinders w/n fire. If your meter lead is a bit bigger than the normal pin size (look at the mating male), then your ground would appear good with the meter, but bad with it hooked up.

As for the PCM, if you do change one, you will need to have it programmed at the dealer for the correct mileage. I'm not sure of these part #'s but I'll give it to you (it may help):

MODULE, Powertrain Control
04606726AD EGE Leaded Fuel
04606760AC EGB California Emissions
04606761AC EGB Federal Emissions
04606762AD EGE w/o P225/60VR16 Tires
04606763AG EGE w/ P225/60VR16 Tires
04606764AD EGE European Equipped

(NOTE: EGB = 3.3L V6 MPI; EGE = 3.5L V6 SOHC 24V MPI)

As for any other culprit, seeing your other cylinders are firing, your ASD must be ok, your crank and cam sensors must be ok, and so I can't think of anything else. Before you do change it, I'd make sure the PCM ground (behind the headlight) is good, (if you haven't already), and make sure the pins/sockets are good at the coil and PCM.

 

Problem Found!

The bolt for the cam tensioner snapped off. The tensioner was flopping to the side and the belt jumped two teeth on the driver's side camshaft resulting in a no-start condition.

I'll be taking the lower timing cover off today and drilling/backing out the sheared bolt.

Saylor

 

Good to hear!

I thought we looked at the belt (back at post #6)? Also I'm not sure how that would make 1 coil not fire...out of time ok, but that's strange. Oh well, as long as it's good!

Kurt

 

I still have to ask if you hear the fuel pump when you turn the key to the on position? You may have had built up pressure in there when you checked for fuel.

 

I only pulled the cam sensor to confirm the belt was spinning, not the belt timing. I could have pulled the cover but with lack of spark to #1 coil that just didn't seem logical.

I put in a new belt/tensioner/bolt and it's back on the road but I'm still baffled why the bolt snapped. I did a google search and there were several instances where folks had the same problem so I can only conclude that it is a design flaw.

Saylor