still rough cold idle after dme temp sensor replaced

[Guest765]

i've checked the afm, the afm temp sensor, and checked out the vacuum lines to the best of my ability. do not have any way to do any compression tests on the manifold/vac lines at this time. fuel economy is poor, rough idle is not nearly as bad as before i replaced the dme temp sensor, but is still present.

any ideas?

[kmakovac]

the AFM have a regulation,maybe you have an errating adjusted CO value when cold and then when the car warm up the O2 sensor engage the right mixture and the iddle was better
i have an AFM open from someone and probably he change the spring relation
the car have poor idle and performance and sometimes dificult to start
i change the AFM and now is OK

try to see the ignition colil,distributor,spark plugs...
try to disengage the iddle valve,maybe is faulty if you have an 85/2 car
try to set a higher idle(1100) when warm and see what happened when cold..

[Guest765]

Originally Posted by kmakovac

the AFM have a regulation,maybe you have an errating adjusted CO value when cold and then when the car warm up the O2 sensor engage the right mixture and the iddle was better
i have an AFM open from someone and probably he change the spring relation
the car have poor idle and performance and sometimes dificult to start
i change the AFM and now is OK

try to see the ignition colil,distributor,spark plugs...
try to disengage the iddle valve,maybe is faulty if you have an 85/2 car
try to set a higher idle(1100) when warm and see what happened when cold..

when warm my idle fluctuates between 900-1100 rpm. it is stable at warm idle, the idle just changes as you drive.
brand new plugs gap checked before install
lightly sanded the cap and rotor contacts to reveal clean brass underneath
no arcing visible from plug wires


if i can find a procedure on clarks garage for the c0 setting i will check it out in a second

[John_AZ]

Check the FPR & FPD for gas leaks. Pull the vac hos off of each and look very carefully for any gas moisture.

Check and clean all electrical connections on top of the engine.

Rebuild the TB (throttle body) with a $20 kit from http://www.arnnworx.com/catalog/

Check the alternator output and battery condition.

Link to www.the944.com ©1999 FR Wilk for CO +++ information.

GL
John

[Guest765]

Originally Posted by John_AZ

Check the FPR & FPD for gas leaks. Pull the vac hos off of each and look very carefully for any gas moisture.

Check and clean all electrical connections on top of the engine.

Rebuild the TB (throttle body) with a $20 kit from ArnnWorx Specialty Tools

Check the alternator output and battery condition.

Link to www.the944.com ©1999 FR Wilk for CO +++ information.

GL
John

battery is known bad, this could cause rough cold idle? i assumed the alternator would take up load as soon as cranking ceased. either way battery is getting replaced asap, hopefully that's the problem.

[John_AZ]

I spent a couple of weeks getting my '87 idle to stop the 925-1050 rpm fluctuation.

Part one.
Swapped alternators (after I tried a new VR) when I found the battery was not being fully charged. The old alt put out enough to keep the idiot dash light out and start the car. I used a hydrometer on the battery and the cells did not charge into the "green" mark. Battery OK with load meter.

Part two.
Cleaned the ICV/ISV with Gumout throttle body and fuel injector cleaner. Cleaned all elecrical connections on engine. Tightened hose clamps and replaced a couple of small pinch clamps with fuel injector hose clamps.

Part three.
I replaced the ICV/ISV hoses and the plastic connector under the "J" boot.

Part four.
Pulled the FPR & FPD vac hoses for the 3rd, 4th 5th +++time.
Saw gas moisture in the FPD!
Replaced FPD.

Idle now is steady at 999rpm

Conclusion:

The car is like a mature woman. Some times you have to do many things to make her happy.

GL
John

[djaychela]

What does FPD stand for?

[John_AZ]

FPD=fuel pressure damper
FPR=fuel pressure regulator

John

[djaychela]

I see! I knew FPR, but didn't know there was a damper - is it on the fuel rail?

[John_AZ]

Yes, the FPD is toward the radiator, the FPR is at the rear firewall side.

John

[djaychela]

Thanks John.

Darren