weird idle on start and hesitation

[1990LTD]

I am thinking fuel filter? I dunno, hasn't been replaced since just after I bought her in July.


Problem: car hesitates when you very slightly tap the gas from a dead stop.....the revs drop down for a split second and then it proceeds as normal. giving it slightly more gas right off of the line, it is fine. no hesitation.



when I start the car normally it revs up high for a few seconds then drops down (was told that's normal operation). now the revs drop down low like I described above - they also drop down when I change directional gears and then return to normal idle. Does not stall. No CEL. The lights dim accordingly.


I am not terribly experienced, obviously, but my first thought is a fuel problem.....I don't know. My alternator belt (what is it actually called?) needs replacing but that is all I know of now that I need but haven't gotten yet. I don't know how to tell if it is slipping, but it does squeak a bit

[79lincolnlover]

The throttle body may need to be cleaned.

[jayh]

iac?

[1990LTD]

I will clean the TB tomorrow when stores are open (none open here on Sundays).



iac?

[jayh]

Idle Air Control

its on the side of the throttle body, take it off and clean it thoroughly

[1990LTD]

Can I use carb cleaner? I've had good results with it. I guess if it'll run through a carb it will run through a throttle body just fine.

[87CrownVic]

Be careful when using carb and choke cleaner in fuel injected vehicles. You can damage the previously mentioned idle air control, as well as other electronic senors downline (MAP,TPS, etc.) I would recommend throttle body/throttle plate cleaner. The 3M aerosol is a couple dollars more than carb and choke cleaner, but I would consider it cheap insurance. Another component to examine would be the throttle position sensor. It could have an open (dead spot) if it is hesitating just off idle. Perform a TPS sweep test as well.

[gadget73]

The alternator belt is called the alternator belt.


A TPS with a dead spot can do this too.

[1990LTD]

This is a used TPS so that is a possibility. I had a CEL last time my TPS went, but I guess it is safe to assume that it could be broken without actually lighting my CEL.

Scottmang sent me a TPS but I sat it on a shelf until I needed it, now the clip that holds it to the harness in the car is broken off. I must have knocked something over on it, I dunno.



Thanks gentlemen.

[pantera77]

20 year old plastic clips break easily. At least half of mine have broken.

[1990LTD]

Any suggestions as to what I could use to keep it on there? I would put a piece of tape on it but engine heat + adhesive = bad times. I could just plug it in and hope it stays together, but I would imagine it's subject to a lot of vibration and would probably fall out.

[jayh]

it will plug together and stay

you can test the tps with DMM

iac is most common

[gadget73]

if you're concerned about it, put a zip tie between the wires and use it to hold the connectors together. Most likely it won't be a problem though. I don't think my car has any clips left on the TPS plug and its been like that for a couple years now.

[1990LTD]

cool guys thanks. i ended up being busy today but tomorrow i'm gonna get some throttle body cleaner and put the tps on.

[jayh]

only make one change at a time!