23 replies to this topic

[Gizmo]

So I searched, but so far it has not been helpful.

The car is a 1996 854 T-5, the only major modification is an MBC, with boost around 13, 13.5 psi. It has been running like this for years.

I was driving home from the country this weekend, about a 300 mile drive. On the way up the car was stupendously well behaved, and so too was I -- no hard accelerations, nothing stupid. ON the way back, my buddy was driving, and on the way up a hill the CEL started up. We slowed, and noticed the car running remarkably rough. Felt like it would stall if I let it, but it hasn't since this started. We limped the thing home, getting much worse than usual gas mileage. Today I finally got my scantool back from my father... A P1310, a P0304, a P0305 and a P0300. So misfire's all around.

My O2 sensor is due for a change, as is my distributor. IS there an easy way to test which is causing this? I'm assuming that my coil is fine, or else the engine wouldn't be running... is that correct?

Should I be suspecting the valves? this was sudden, and the motor has been very well behaved recently.

[the commissar!]

How long since you checked stage zero stuff...I d start there. Easy and cheap...plugs & gap, wires ok? or old, distrib and rotor ok or old? Fuel pump relay or pump ok? Eliminate the easy things and then look for something bad if you have to

[Gizmo]

the commissar!, on 03 November 2009 - 10:02 PM, said:

How long since you checked stage zero stuff...I d start there. Easy and cheap...plugs & gap, wires ok? or old, distrib and rotor ok or old? Fuel pump relay or pump ok? Eliminate the easy things and then look for something bad if you have to

Could the fuel pump/relay be causing this? I guess another way of putting the whole question is, is there an easy way to tell if the problem is due to spark issues versus fuel issues?
Plugs are brand new, wires and distributor/rotor could use replacing. Injectors are in great shape, but the relay, pump and filter are getting on the old side. IN a perfect world I'd replace all of them, but I'm less employed than I used to be.

If there's no simple trick, I'll start one by one, starting with the distributor, as that's the oldest. When I start checking wires, what kind of ohm readings should I see from healthy wires?

[Cal3thousand]

Gizmo, on 03 November 2009 - 10:18 PM, said:

Could the fuel pump/relay be causing this? I guess another way of putting the whole question is, is there an easy way to tell if the problem is due to spark issues versus fuel issues?
Plugs are brand new, wires and distributor/rotor could use replacing. Injectors are in great shape, but the relay, pump and filter are getting on the old side. IN a perfect world I'd replace all of them, but I'm less employed than I used to be.

If there's no simple trick, I'll start one by one, starting with the distributor, as that's the oldest. When I start checking wires, what kind of ohm readings should I see from healthy wires?

MAF, FP, FP relay, FI relay

All these things above fail eventually. The question is not if, but, when.

Since you are in a situation like many people and can only afford to do some repairs at a time, test everything.

For fuel related items, testing pressure on the rail at different moments will give you clues. You could also jumper the FP relay to see if that alleviates your problem.

But when you say misfires, it makes me think that its an ignition or sensor related issue rather than fuel delivery. To me, fuel issues generally hit harder than limpy performance (ie stalled car, occasional no starts and intermittent behavior)

How is your vacuum at idle?

[Gizmo]

Vacuum at idle is healthy. First instinct was to check for leaks, but everything seems good, both on the dash and poking around under the hood. This misfires seem worst at idle, with a very harsh, loping idle, and strong vibration in the cabin. It doesn't strike me as fuel related either, unless the ECU is compensating for a dead 02 sensor. I clean my MAF regularly, as well, so I dont think its that.

I'll check the relays, but my gut is its the distributor cap.

[Bah]

Might be a stretch here, but, whens the last time the Timing belt was inspected?
I've heard of the timing belt jumping a few teeth...i'm sure it wouldnt hurt to just inspect it. Otherwise i agree with the distributor cap area =)

[JordanW]

Gizmo, on 03 November 2009 - 10:18 PM, said:

Could the fuel pump/relay be causing this? I guess another way of putting the whole question is, is there an easy way to tell if the problem is due to spark issues versus fuel issues?
Plugs are brand new, wires and distributor/rotor could use replacing. Injectors are in great shape, but the relay, pump and filter are getting on the old side. IN a perfect world I'd replace all of them, but I'm less employed than I used to be.

If there's no simple trick, I'll start one by one, starting with the distributor, as that's the oldest. When I start checking wires, what kind of ohm readings should I see from healthy wires?

What brand of spark plugs did you use?

[TyConn]

Bah, on 04 November 2009 - 07:43 AM, said:

Might be a stretch here, but, whens the last time the Timing belt was inspected?
I've heard of the timing belt jumping a few teeth...i'm sure it wouldnt hurt to just inspect it. Otherwise i agree with the distributor cap area =)

+1
+200 if i could

[TRACStar]

Gizmo, on 03 November 2009 - 11:17 PM, said:

This misfires seem worst at idle, with a very harsh, loping idle

That screams ignition to me.

Change the cap and rotor, if there is no change check/replace the coil. Its one or the other since its affecting all cyls

[Gizmo]

OK, just replaced the cap and rotor, and there's no real change. Still pulling P1310, P0305. Was going to check my wires when I discovered that someone over-tightened and nearly stripped my Spark plug cover bolts... (there's a mechanic no longer frequent, and this kind of thing is why. Any tricks to getting those off? I've torched suspension bolts before, but I'd really rather not torch my cover)

Anyway, plugs are new Champions. I've been running non-volvo Champions and NGKs for at least the past two years, and the engine has seemed to love them. Cant tell how they're doing until I get this damn cover off (anyone want to sell me a new one whilst I dremel this one off?)

Is there an easy way to diagnose a coil? an old wrench once told me to shake it and see if it sounds dry inside? I agree with the consensus here that this seems to be ignition-related. Engine smells a little rich when running, and I doubt I could have made a 300 mile run on a fuel starved engine...

Oh, also, the timing belt is brand new. Maybe 2000 miles on it, max.

[Gizmo]

Replaced the coil with a known-good generic Delco-Remy from my Uncle's garage. No effect.

Also, noticed that as the engine runs rough, the cabin lights pulse ever so slightly (can't notice it in the headlights).

So this is an electrical issue of some sort.

Any suggestions?

Car smells quite rich. I'll kill my cat and o2's if I keep running it like this.

[Gizmo]

Maybe I'm going about this all wrong. Could this be a bad MAF? Would that cause it to run rich and misfire? (methinks no, but there are smarter people than me around here)

[mrbrightside2009]

Gizmo, on 08 November 2009 - 10:53 PM, said:

Maybe I'm going about this all wrong. Could this be a bad MAF? Would that cause it to run rich and misfire? (methinks no, but there are smarter people than me around here)

if its a bad maf, the car would probably stall and eventually just shut off right after you start it, also should get a code, you can try unplugging the maf and see if the car runs ok, then you know for sure. misfire codes i don't believe would be a maf issue.

[Gizmo]

Is it possible that symptoms aren't resolving because running for 200+ miles with a non-firing cylinder would foul the plug? Such that even if I've replaced the faulty part (the coil or the cap/rotor), there's still a fouled plug? It might explain why I'm no longer pulling a p0304

[Gizmo]

OK. New plugs, new wires. Old plugs all looked good, except #5, which was covered in either light oil or fuel. Plug wire 5 was arcing. New Champion RC9YCs, New wires. Looked into the cylinder on #5, and it looked filthy. Seafoamed the engine, Put in some injector cleaner, went out and tried to have a rev-fest.

ECU's still throwing p1310s and p0305s left and right.

Plugs wires and cap/rotor all new. Car s going through fuel ridiculously quickly. What gives??

Going to try to check the timing tomorrow.

[Gizmo]

Any ideas?

Someone over on Turbobricks suggested that I pull the rail, throw the ignition to position II, and see if injector 5 starts spewing fuel. And then replace the ECU and the injector if it does.

Not sure how I would have toasted my ECU. Does this sound like a reasonable theory to you guys? A constantly spraying injector would certainly account for the fuel loss and the grime on the plug and piston...

Can we re-cap my options here?

Coil ....... Replaced
Plugs ...... Replaced
Wires ...... Replaced
Cap/Rotor .. Replaced
Timing
Valves
ECU/Injector

Am I missing anything? Should I go back to looking at the fuel side of things?

[Gizmo]

OK. Checked the injectors tonight with the ignition in position II. No spray, no dribble. When I accidentally took off the line to the rail, fuel was flowing. So. what other theories are there?

Ruled out cap, rotor, plugs, wires, injectors, coil and at least the fuel management part of the ECU. Shop that installed the T-belt agreed to check the timing for free Thursday. What else should I test before then?

Camshaft position sensor? is that a possibility? would that be throwing its own code?

[Bah]

If not the CPS, im putting my money on a valve in Cyl #5 either stuck or broken maybe....

Compression test i guess is the next route?

[Gizmo]

Bah, on 11 November 2009 - 06:36 AM, said:

If not the CPS, im putting my money on a valve in Cyl #5 either stuck or broken maybe....

Compression test i guess is the next route?

Compression test is next.

How would a stuck valve work? If it were stuck open, I'd have broken it off around mile.... 5 of the two hundred or so the car's been asked to drive in this condition, and I'd have gotten some serious knock and further destruction over the next 195. If its stuck closed, would my camshaft still be able to rotate?

Also, could it in fact be a CPS? elsewhere I've read that the CPS is a culprit for non-start situations, but I've been cranking and starting pretty easily.

Thanks for your help guys. Its nice to know I'm not the only one this is confounding.