Acting Wierd

[zrice88]

Many of you know I had a running problem with my 1990 Festiva L 5-speed. I replaced the crankshaft position sensor and adjusted the throttle position sensor and now she runs like a dream. But I have another problem with the same car.

When the car is warm she idles at a about 900-1000 rpms. When I come up to a stop light and hold in the clutch the rpms drop to about 400-500 rpms.

If I put the car in neutral and let out the clutch the idle goes back up to where it should be. But the moment I step on the clutch the idle drops.

I tried adjusting up the idle but it makes no difference. The idle still drops to the same place.

It hasn't died on me yet but it seems that it might if I hold the clutch in long enough.

Has anybody encountered this problem before? Any help would be appreciated.
Thanks

[zrice88]

nobody has any ideas at all? BTW it still misfires. it was better for about a week after i put the new crank sensor in and then it started acting up again.

[IL4Festiva]

what do you mean by misfires? missing a cylinder, or backfiring?
you say 900-1000 when the car is warm? does this change when it is cold?
I do not know enough to diagnosis this myself, but i will ask somone who knows more than i and look into it for you.
is 900-1000 what you normally have your idle set to or is this a result of the problem?
I will do my best to find out what i can.
Sean

Just a thought for people who know more than i, is there any electronics attached/used in the clutch system that could be drawing power at all in the festivas?

[zrice88]

idles normally at 900-1000 rpms. idles higher when cold 2000 rpms usually. one cylinder doesn't seem to miss. it seems like they all do it at the same time

[IL4Festiva]

you mean as if all 4 cylinders were to skip a combustion stroke?
do the rpm's keep dropping, or does it stay at a steady 4-500 and just feel like its going to stall?

If it misses all 4 cylinders in one revolution, it makes me think that your not getting enough power to something electrical and that might make up for your very low idle but it still does not make a whole lot of sense.
i wish my haynes wasnt at the shop :evil:

[IL4Festiva]

i don't know if this will help or not, but i found it on the web and it has some useful information, i'll read it over but you definitly want to check it yourself or another experienced member.
sorry if it isnt what your looking for, but i figure a little help is better than none.
Sean

http://books.google.ca/books?id=V6KVydlB0J0C&pg=PA52&lpg=PA52&dq=clutch+open+idle+drops&source=web&ots=STj6M7H9he&sig=sEmmYK4r-R4xN17p9OA4nwIy87I&hl=en#PPA52,M1

it is a little online book about ford fuel injection, chapter 7 has alot of information about devices related to the clutch that regulate idle speed and other various things (all this stuff is way over my head) Good luck man, and i hope it will help you out!

[IL4Festiva]

does anyone know if festiva's have neutral drive switch's?
"the Neutral drive switch detects when the transmission is placed in neutral. When the transmission is placed in gear, the torque converter and transmission become an additional load on the engine. This load can cause the idle speed to drop. When the ECA (i think they mean ECU) senses that the transmission is placed in gear, it increases airflow into the engine by means of the idle control device. this increase in airflow prevents a dip in rpm as the transmission engages into drive or reverse"

im guessing that is only for automatic transmission.

but there is an Neutral gear switch for manual transmission which warns the ECU that there is a potential load may come onto the engine and ECU is then prepared to increase idle to prevent a stall.

Could a faulty neutral gear switch cause this problem?

[jglutz]

IL4....that's an AWESOME link....What i've been looking for for a long time. I've been trying to locate and buy a Ford Powertrain book for years...I'm going to investagate the Watson publication.

Anyone....have you ever used this book before? If so, is it useful?

[FB71]

Keep in mind, the Watson book covers EEC-IV, which was the EFI system for domestically built Fords Lincs and Mercs. Our cars use Mazda MECS, which is a significantly different system. Just an FYI.

[IL4Festiva]

Ahhh, maybe there are other books that cover mazda mecs than? let us hope i suppose.

I wonder if this is a possible ECU problem in Zrice's car,
trying another ECU unit from another car that doesn't have that problem would atleast let u know its not your computer.

No one else has any idea's what could be going wrong?

[scitzz]

My baby car has done this for so long, I don't even notice it anymore.....would be interested in finding a fix if I had the time....

[jglutz]

Keep in mind, the Watson book covers EEC-IV, which was the EFI system for domestically built Fords Lincs and Mercs. Our cars use Mazda MECS, which is a significantly different system. Just an FYI.

Thanks, Jim:x ....I'll get my powertrain book someday

[Burnrate]

Ther is also this book.

http://www.bentleypublishers.com/product.htm?code=GFF9

Eric

[kzbill]

As FB71 says so often, "check da battery"!

[IL4Festiva]

Ther is also this book.

http://www.bentleypublishers.com/product.htm?code=GFF9

Thanks! that is wicked, i might order one in the near future.