Misfire on cylinder 1 and 5

[tripletdaddy]

I'm not saying the cps idea is wrong, but if it is misaligned I don't understand why it would only affect a few and not all of the cylinders. If the timing advance is off, it is off for all of the cylinders. Right? I don't understand how something that would affect all would only show symptoms with just a few. Or am I trying to be too logical and can't apply my thinking that way?

[serge_saati]

Because the timing advance is not totally off. It can be retarded of few degrees only so the engine is not at its optimal efficiency.

When the engine is running slow (<2500 rpm) and the gas pedal is not presed too much, almost all the gasoline can burn in the cylinder.

But when the engine is running fast in third gear (>3000 rpm) and the gas pedal is pressed a lot (at high speed, high acceleration and at uphill), a lot of fuel enter in the cylinder in a small period of time and the fuel is not totally burned. Especially if the spark timing is retarded of 5 degees and more.

It doesn't happen often, but when it happens, only one pair of spark plugs can be affected so this pair of cylinders misfire only. Because all the spark plugs doesn't fire all in same time. Only two at same time. If the engine misfiring, its rotary speed will be mechanically reduced, and the other cylinder will not misfiring.

It misfires only when it reaches a specific power and engine speed.

In one trip, only one misfiring can occur. One misfiring affects two cylinders.
If paradigmlxi scan his car after each long trip, he will detect other misfired cylinder.

[wiswind]

As you mention that you "had" the work done, I would go back and explain the problem.
They may know right off what to check.
Ask them if they can check the Camshaft Position Sensor (CPS) for you.

Sometimes the mechanics at the shop have seen enough of the same vehicles, with the same issues.....that they can go right to the solution.

[jayjp200]

I had the same problem 2 years agon on my 3.8 lit 1998 windstar. I removed the intake manifold. the EGR holes on 1 & 5 were completely plugged. I cleaned them, EGR passages and replace the manifold seals.
The problem is gone.

[Gobowiec]

I've searched forum and this thread seems to be best to ask about timing advance. What should be timing at idle? With everything off (AC, vent, radio, in Park...) I get timing advance 15-16. Shouldn’t it be 10-11 degrees? Putting anything on (shift to Drive) causes it to rise up to about 20-25, during drive I get 30-40. Are these readings correct?

[serge_saati]

The base setting is 10° at idle. When the engine accelerate and the load increase on the engine, the timing increase to have enough time to burn all the fuel. It's normal that your timing increase. But it's too high at idle, you need to test your ignition system with a timing light to see if your PCM is good or not. Or you need to adjust the CKP sensor position.

[Gobowiec]

I'll just make a copy-paste:
Initial engine ignition timing is set at 10 degrees ±2 degrees before top dead center (BTDC) and is not adjustable.
The crankshaft position sensor (CKP sensor) (6C315) is a variable reluctance sensor triggered by a 36-minus-1 tooth trigger wheel located on the crankshaft pulley and damper.

So I guess theres nothing to adjust. I also found something like this and made a pdf file:
http://www.wrzuta.pl/pliki/ljYsbGvaIs/
click the "ściagnij plik >>" link to open the pdf.
The timing advance I get from OBD2 reader are within limits SPARKADV from file.
PS. If someone would like similare table for a 3.8l engine I can upload such and pass the link. This is a Polish site for hosting, and it doesn't pass garbage when downloading. If you pass me other host site adress I'll upload it over there

[serge_saati]

You are true about the crankshaft position sensor. I just talked about ultra fine tuning when you screw it on the timing cover. You can move it about 0.04", but it's not very important.

I suggest you to try the timing light test to see if the marks on the pulley is aligned with the one on the timing cover. It could indicate a misconfigured PCM.

I think that your PCM don't have the factory setting. This is possible.

[derffred]

read my thread http://www.automotiveforums.com/vbul...d.php?t=903467
you may get some ideas from that

be sure to make shure that you have no vacumm leaks, that was my worst problem

[serge_saati]

It's an interesting thread. Very complex!
But it can't explain the incorrect ignition timing advance of his van.
So I think that he has an timing advance problem.
Gobowiec, does your problem is new, or you alway got this problem?
Have you made modification, or it happen like that?

I suggest you to connect your OBD2 port to a computer and run a program than can tune your car. You can adjust your timing advance like that, by programming the PCM. It should correct your misfire problem.

[derffred]

but, I think that a vacumm problem can give you the syptoms of timing being off.

someone else had a problem with a crank pully that was not balanced which gave similar problems too

if it indeed is a timing issue maybe a crank sensor??

at any rate while the idea of using a computer to fix the idle may work it may only treat the symptom not cure the ill., I still think I would check and recheck all of the vacumm hoses

[serge_saati]

I don't think so. The timing is triggered only by the CKP sensor and the PCM. The vaccum hose and everything else don't interfere with the ignition.
Vaccum problem can cause misfire but no ignition problem.

If it was the CKP sensor, the engine will not run at all. So it's not that.

It's obvisouly a bad setting in the PCM.

Gobowiec, test your ignition with the timing light to be sure. Sometime the onboard system diagnosis don't give you the right timing value. Because the PCM can be slow to react.

[tripletdaddy]

Just for clarity on the CMP and the CKP, I have quoted from my Haynes manual the following, which I also cross referenced with Ford's Service manual to assure accuracy:

"the camshaft position sensor (CMP)...sends a voltage signal pulse to the PCM to indicate when the number 1 piston is approaching TDC on the compression stroke. The PCM uses this signal to synchronize and sequence the fuel injectors."

"The crankshaft position sensor (CKP)...signals to the PCM when the crankshaft is 60 degrees before TDC for cylinders 1 and 5. The PCM then... uses this information to control ignition spark advance. The CKP also provides the engine speed signal to the PCM and is part of the misfire monitor circuit...The OBD-II system can detect different CKP sensor problems and set DTC's to indicate the specific fault."

As per above the CMP does play a role in the ignition, though it is not as critical as the CKP. I have not independently verified for myself, but others have stated that the ignition system can still function relying only on the CKP if the CMP isn't working. However, a bad CMP should give a DTC like "P0340 Camshaft Position (CMP) sensor circuit malfuntion", but it can be manually tested if you doubt the lack or validity of a code. As per above the CKP will give a DTC if bad, but it too can be tested to verify its condition.

If this is an evasive timing misfire issue and all other normal avenues have been pursued fruitlessly, have you checked that the cmp and ckp are exactly position correctly? If you are suspicious of either, maybe try a borrowed or new one. You have definetely ruled out, replaced the coil, wires, plugs, and whatever else? Egr and opening cleaned? Pressure tested the cylinders?

[tripletdaddy]

I copied this from Wiswind's code thread from the top stickies. What caught my eye was the fact that the CEL will flach during a misfire event(s). He also lists several good things to look at, especially the fuel injectors.

"Misfire can be caused by a spark issue, spark plug, spark plug wire, coil pack. or by a dirty fuel injector (very common), or nonfunctioning fuel injector
CEL will flash when misfire is happening indicating possible condition that can harm the catalytic converter(s) because if caused by no spark, raw fuel can be entering the catalytic converter.
Do a search on your P030x code for more information."

[derffred]

on mine I had misfire codes on 4 and I changed the injector, then retested and had code for 2&5 so I changed those, it was while changing them that I noticed the vacume hose going to the evap being snapped off, I am wondering if that was my problem and my injectors were actually ok.

from my Haynes manual talking about the EVAP (Page 6-16)
Poor Idle, Stalling and poor drivability can be caused by an imoperative vapor managment valve, a damaged canister, spilt or cracked hoses connected to the wrong ports.
So the evap can cause the same symptoms as misfires in the cylinders. not saying that this is his problem at all, but still worth checking.