sorting thru some issues and decided to start with cap and rotor, ** updated to 11/20 - 3 issues causing 3 overlapping problems- resolved Options

[DRPHIL914]

I have not seen scratches like this before in a cap.; bad rotor?

- see the last post-
1 bad CHT
2. bad TPS
3. bad f.i. injector trigger points plate.

NOT MPS,
NOT cap, rotor(although i did replace these too)

[fixer34]

What's the rotor look like? The scratches are behind the terminal posts (?). Something sticking out of the rotor and bouncing around?

[bdstone914]

did you ever turn over the engine with the cap loose? Are the marks on both sides? What symptoms were you having that made you start looking for a problem?
Bruce

[DRPHIL914]

did you ever turn over the engine with the cap loose? Are the marks on both sides? What symptoms were you having that made you start looking for a problem?
Bruce

You know I do remember doing that a while back, but never checked the cap after that .b
Why I was looking? I've been getting a weird sudden skip, miss, and also out of nowhere while idling normal it will suddenly act like it's going to die. Not the same as a surge. It goes from idle at 12-1300 and suddenly drops to like 5-600, . It started with just a hot start kind of thing , where it would not idle right when stopping and engine is hot, on restart it doesn't want to stay running for 30 seconds or so then will do o.k. now its doing this out of nowhere even with out turning it off.

[bdstone914]

did you ever turn over the engine with the cap loose? Are the marks on both sides? What symptoms were you having that made you start looking for a problem?
Bruce

You know I do remember doing that a while back, but never checked the cap after that .b
Why I was looking? I've been getting a weird sudden skip, miss, and also out of nowhere while idling normal it will suddenly act like it's going to die. Not the same as a surge. It goes from idle at 12-1300 and suddenly drops to like 5-600, . It started with just a hot start kind of thing , where it would not idle right when stopping and engine is hot, on restart it doesn't want to stay running for 30 seconds or so then will do o.k. now its doing this out of nowhere even with out turning it off.

Mailed you replacement TPS. Maybe that is it.

[DRPHIL914]

did you ever turn over the engine with the cap loose? Are the marks on both sides? What symptoms were you having that made you start looking for a problem?
Bruce

You know I do remember doing that a while back, but never checked the cap after that .b
Why I was looking? I've been getting a weird sudden skip, miss, and also out of nowhere while idling normal it will suddenly act like it's going to die. Not the same as a surge. It goes from idle at 12-1300 and suddenly drops to like 5-600, . It started with just a hot start kind of thing , where it would not idle right when stopping and engine is hot, on restart it doesn't want to stay running for 30 seconds or so then will do o.k. now its doing this out of nowhere even with out turning it off.

Mailed you replacement TPS. Maybe that is it.

Got it today, I will be testing it tomorrow!

[Jon H.]

out of nowhere while idling normal it will suddenly act like it's going to die.

Mine would do that at stop lights etc, and I adjusted the mixture screw on the ECU and it fixed the problem with mine (IMG:style_emoticons/default/confused24.gif)

Jon H.

[DRPHIL914]

so since i last posted about this, i have tried a couple things. replaced that TPS and that made a huge difference in running down the road, and might have effected the idle in a positive way, but i replaced the CHT with a brand new one, then started it up and once warmed up to temp i began adjusting the part load on the MPS because it was running way too lean, and i believe that was much of the idle issue , so it ran great on saturday for a half hour trip - (also put a new coil in )
parked the car and the is what happened this morning: (also posted to the "what did you do to your 914 today" thread):


i TRIED to drive it today but (IMG:style_emoticons/default/headbang.gif) it didnt want to start, partly because i think the battery is getting weak, but it usually cranks up on first turn, but it was like it was missing or not firing on all 4, like if i had bad points but i have hotspark module-
Saturday it ran fine, after putting in new coil, drove for 15 miles for test drive, ran perfect, came home, idled in driveway for a few minutes while i was monitoring temp and checking A/F readings, then parked it. That was just 4 days ago, so (IMG:style_emoticons/default/confused24.gif) . almost started, was very rough, died, then would not get going.
didnt have time so i gave up and drove the other car to work. (IMG:style_emoticons/default/sad.gif)

i'll re-check grounds tonight and maybe switch out the points module and/or FI points and see if that makes a difference- but if feels like a spark/electric issue not fuel.
(IMG:style_emoticons/default/hissyfit.gif)

so im not sure what i am missing- just does not make sense

[r_towle]

So, a stock motor should not need any adjustment on the MPS.
If it's running lean, it's either a vacuum leak or your timing is to advanced.
You could also have issues with the TPS not being installed correctly and setup to be on the correct idle circuit when at idle.

If the CHT is unplugged or that wiring is compromised, the car won't start.

One thing to consider, and many of us have had to deal with this...
The old brittle FI wiring harness will be darn near impossible to rule out until you test every circuit with an ohm meter.
Pull off the main plug from the ECU and ohm out each wire.....
These old wiring harnesses will give you all sorts of issues, and they change each time you do anything new.

Just touching the harness to install things can create a break.
Rich

[DRPHIL914]

So, a stock motor should not need any adjustment on the MPS.
If it's running lean, it's either a vacuum leak or your timing is to advanced.
You could also have issues with the TPS not being installed correctly and setup to be on the correct idle circuit when at idle.

If the CHT is unplugged or that wiring is compromised, the car won't start.

One thing to consider, and many of us have had to deal with this...
The old brittle FI wiring harness will be darn near impossible to rule out until you test every circuit with an ohm meter.
Pull off the main plug from the ECU and ohm out each wire.....
These old wiring harnesses will give you all sorts of issues, and they change each time you do anything new.

Just touching the harness to install things can create a break.
Rich

Rich ,
i appreciate the input, - i should have included more info-
the wiring harness was a complete new replacement FI harness and ignition harness from Jeff Bowlsby last year so unless a connector came loose we can eliminate that as the issue.
- i have beendown that road with vac leaks, and thats not it here now, every hose seal etc was replaced last year, and had been running pretty good, but the wierd idle issue was not a up and down constant surge like you get wiht vac leaks - it would run fine but after idling for a while out of no where i would get a sudden drop in rpm, almost die, then rev it a bit and it would level out- seemed only to be when hot- so i replaced the cht(because with in line resistor the issue got better)-it was llike a hot start thing -
- MPS_ i have 2, bought second hand- the original one is long gone- when i bought the car it would not run due to a shot MPS(previous owner had it mounted up side down and left it out- it had water in it!, ordered a rebuild one from ecklers- that one went bad fast, replaced again, - then bought a box of cores and found 2 with good inners but had been messed with, - sent them to a friend that has an LCR meter and was able to reset them to factory specs, have the proper curve and re-sealed them. They both are 043's and are leak free. - but at factory spec they are still too lean, - so they did require a bit of richening out across the board-
and the one in there now - on saturday, had me running @ 12.5 across the board, .
- from here it seems like its not either of those 3 issues regarding the rough start th/ missing this morning.

phil

[DRPHIL914]

It appears it was the mps! Put the unmolested one in , let it sit for a while because it was flooded out and started right up! Now I need to pull this other one apart since I have a rebuild kit , see if it's the diaphragm because it holds vac fine.

[r_towle]

This pic is at idle.
It's a special circuit for idle only, but it affects the overall running cause if you set it wrong all your fuel/ air settings ( which are based upon the position of the sensor) could potentially be off by one notch...which is enough to give the results you are experiencing.

May not look exactly the same, but the principles apply.
It is not adjustable.
Set it and forget it.
There is only one way to set it on each car or throttle body.
Use the picture below as reference, but the key is the idle circuit setting which is unique and set with the throttle body fully closed.

Rich

[DRPHIL914]

This pic is at idle.
It's a special circuit for idle only, but it affects the overall running cause if you set it wrong all your fuel/ air settings ( which are based upon the position of the sensor) could potentially be off by one notch...which is enough to give the results you are experiencing.

May not look exactly the same, but the principles apply.
It is not adjustable.
Set it and forget it.
There is only one way to set it on each car or throttle body.
Use the picture below as reference, but the key is the idle circuit setting which is unique and set with the throttle body fully closed.

Rich

thanks for the pic!. I am going to double check this tonight and make sure it is set correctly.
I am pretty sure i have some other issue that i have not identified because last night. as i had posted it would not run - period. then suddenly it just fires right up perfect like nothing had been wrong- i had been fiddling around with connections, and replaced the MPS but i think it was coincidence. i think it s a bad or loose connection because it comes and goes like that. - you had point ed out the issues that will arise from old wiring harnesses and thats why i replaced mine. but this does act like that and i might have just pulled on or bumped something while in there and bam, just like that ran like brand new- got home ran fine. parked it 20 minutes started right up went home fine. -

--- went to start it this morning - started rough, like it was missing or skipping and like it didnt want to stay running, i had to keep feathering the pedal thought it was ok, then began to miss and died. - fuel pressure is perfect, - but what changed from last night to this morning? weird. but it seems like its a bad connection. (IMG:style_emoticons/default/confused24.gif)

[boxsterfan]

See if you can borrow someone's MPS.

[DRPHIL914]

See if you can borrow someone's MPS.

i was thinking this, - or maybe i need to have a second car - (IMG:style_emoticons/default/idea.gif) - cheaper to just get a new - or borrow - a MPS - - i do have 2 and i switched them last night and thought that was it but now i dont think that s it. the replacement MPS was at 12.5 at part load and full out acceleration, cruising, and @11.5 at idle after warmed up , that was a total of 30 minutes driving and testing. - i think that MPS is fine- holds vac perfect.

- but i am atht is point seriously considering getting that 2.2 / 6 for sale in the classifieds (IMG:style_emoticons/default/shades.gif) EDIT: never mind that- a day late and a dollar short it looks to be sold-

[dknechtly]

How's the resistance at the trigger points? It doesn't take much to make it run lean. Don't use emory cloth; it is too coarse. A note card or jeweler's cloth works.

[DRPHIL914]

How's the resistance at the trigger points? It doesn't take much to make it run lean. Don't use emory cloth; it is too coarse. A note card or jeweler's cloth works.

do you mean the injector trigger points? I have a points module (hotspark)- same as compufire. ive been running it for 4-5 years. but i have a second one and i might switch it out as part of my trial and error just to see if it makes a difference.

[Java2570]

Trigger points are a module screwed into the base of the distributor and look like this:

[DRPHIL914]

Trigger points are a module screwed into the base of the distributor and look like this:

i was just trying to clarify if you were referring to these or the other points. -
I actually have another set of these i bought from bruce stone and i was going to switch them out last night before it started to run fine so i left them alone.

[DRPHIL914]

I did not pull the distributor and look at the f.i. points yet. I did recheck the timing and it's spot on. I also readjusted the t.p.s. as suggested above. This seems to have helped . Drove fine tonight so we will see how it starts tomorrow.