ruff idle + missfire

[brapple]

lets see, A friend of mine recently built a 3L hybrid for is 98 Mystqiue after the 2.5 let go at about 150k.

the 3L was from a taurus and we build a hybrid. Now the engine runs and has been since May or so.

Issue is the engine has a very rough idle, it shakes the whole car, mainly the dash. When the engine is at a high idle ~1k rpm or higher the engine is relatively smooth. Now the engine was originally build with all stock componenets. It has been upgraded to 19# injectors and a SVT PCM which all help how its running but the idle is still pretty rough. Also it is continuously getting miss fire codes on #1, 2 and 3. Plug wires are used Ford Racing wires but again the engine run good at high rpm.

we are thinking that the timing is either off on bank 1 or the tensioner is bad. Also I am not sure what tensioners where used but they may have been the 3L tensioners, not sure at all which chains where used.

So bottom line I believe is that the front of the engine needs to be openned up and the timing check.

any one have any other thoughts?

[JScullin]

Check those Ford Racing wires. I've had 2 go bad on me out of the blue and it caused a nasty misfire and shake. But ran relatively smooth when under load.

[brapple]

Check those Ford Racing wires. I've had 2 go bad on me out of the blue and it caused a nasty misfire and shake. But ran relatively smooth when under load.


can do but i believe they where installed after the engine was build and running again so I don't believe that is an issue. I just had my set go bad and it idled fine but missed under load ....

[aircougar1]

Check those Ford Racing wires. I've had 2 go bad on me out of the blue and it caused a nasty misfire and shake. But ran relatively smooth when under load.

I really believe its the same thing.... as i have been hinting to Roger for a while now. I have been lucky that my FRP wires haven't had any noticeable problems yet, but I would think its the problem he is having.

[brapple]

ok, I have a set of stock wires which are still good, I'll see if Roger wants to try that and if it makes a difference

you know, what am i thinking ... first thing should be to change the wires if there is a misfire ... learned that a few time on my families cars ...

[brapple]

ok, fitting a set of stock wires that I have which I know are good and it didn't make any difference.

[fordrule]

well the unfortunate has come and you might need to get into the timing

[warmonger]

ok, fitting a set of stock wires that I have which I know are good and it didn't make any difference.

Also check and make sure the type of plug is compatible with the stock double plats with those stock wires and maybe tighten the gap a little bit. See if that changes anything. The wires and plugs go hand in hand towards setting the right resistance in the coil circuit and generating the correct spark.

[SicSE]

Sounds like a compression problem. And with miss codes on the whole bank, I'd say you're on the right track with a timing issue.

[brapple]

In case anyone was wondering we got it straightened out yesterday. We went into the engine and retimed it and used different guides and chains also. The idle is pretty much smooth now, seems to just hickup alittle every so often but so far the miss fire and ruff, ie engine shaking idle is gone. Car still has great power.



Also check and make sure the type of plug is compatible with the stock double plats with those stock wires and maybe tighten the gap a little bit. See if that changes anything. The wires and plugs go hand in hand towards setting the right resistance in the coil circuit and generating the correct spark.

plug are autolite APP764's. when I pulled them yesteray the gap was tight, around 0.040 so I openned them up as close as I could get them to the stock 0.054 gap.

question, should a hybrid go tight on the gap because of the compression or stick with the stock spark plug gap?

[Topik]

the hiccup is most likely the coil pack

[fordrule]

has anything helped? or worked

[aircougar1]

Read a few posts back... :rolleyes:

[brapple]

my understanding is that the car is running great at this time, it made a good road trip the following thursday night and performed very well