Slight hesitating pulling away from a stand still.

[SIMid]

Just noticed the last couple of times I have driven the car, I noticed a very slight (occassional) hesitate on the engine as I pull away from a stand still.

I did get the distributor and rotar changed by my mechanic over a month ago (new sparks 8 months ago) and he also removed the intake to get access to it. When I picked it up, all is good. Only just recently she started this little hiccup.

She wont stall, just a very slight pause taking off, not enough for the engine revs to drop too drastically. This wont happen all the time, only the occasional take off. It happens with the A/C on or off.

Thought I'll ask before anything serious happens (like being stranded on the side of the road).

Any ideas?

[Jonathan]

If it's the kind of hesitation where pressing the gas doesn't immediately translate into the engine speeding up, you might have developed some slack in this:

http://store.delorean.com/p-6409-rod-assy-throttle.aspx

It's what goes between the throttle cable spool and the butterfly valves lever arm. The sockets on the two ends can get sloppy or the linkage itself may require a length adjustment. If you take both ends off, you can adjust it almost infinitely for length. If you only get the end off near the spool, you can only adjust the length via one complete rotation (so that the sockets line up again when you reinstall).

[NightFlyer]

She wont stall, just a very slight pause taking off, not enough for the engine revs to drop too drastically. This wont happen all the time, only the occasional take off. It happens with the A/C on or off.

Does it only seam to happen when the engine is cold, such as within the first several minutes after a cold start-up?

[SIMid]

Jonathan, it only happens occassionally and only when warmed up that I had noticed. If there was some slack, wouldn't it be like it all the time? Just trying to think it through.


Does it only seam to happen when the engine is cold, such as within the first several minutes after a cold start-up?

No, strangely when the engine has warmed up. No issues starting hot or cold.

[NightFlyer]

Jonathan, it only happens occassionally and only when warmed up that I had noticed. If there was some slack, wouldn't it be like it all the time? Just trying to think it through.

No, strangely when the engine has warmed up. No issues starting hot or cold.

As opposed to a slacked throttle cable, what about a sticky/un-lubricated throttle cable linkages. As the existing lubricant heats up, it loses its viscosity and causes stickiness in the operation of the cable and linkages.

My best guess at this point....

[SIMid]

As opposed to a slacked throttle cable, what about a sticky/un-lubricated throttle cable linkages. As the existing lubricant heats up, it loses its viscosity and causes stickiness in the operation of the cable and linkages.

My best guess at this point....

I might get my mechanic friend to take a look at it. Sounds possible.

[Bitsyncmaster]

Most of the time, hesitation is caused by improper mixture (AFR). Have you had the mixture adjusted with a dwell meter? You adjust it with a warmed up engine.

[SIMid]

Most of the time, hesitation is caused by improper mixture (AFR). Have you had the mixture adjusted with a dwell meter? You adjust it with a warmed up engine.

I have not touched it, unless my mechanic fiddled with it when he took the intake off to change the Cap and Rotor. Next time I take it out, I'll have a fiddle with it. I heard even a quarter of a turn causes drastic changes.

Thanks for the suggestion Dave.

[DMCMW Dave]

I have not touched it, unless my mechanic fiddled with it when he took the intake off to change the Cap and Rotor. Next time I take it out, I'll have a fiddle with it. I heard even a quarter of a turn causes drastic changes.

Thanks for the suggestion Dave.

Yeah, even an 8th of a turn is drastic. If he fixed any vacuum or unmetered air leaks in the process of R&Ring the intake, it would change the required setting as well.

[David T]

Yeah, even an 8th of a turn is drastic. If he fixed any vacuum or unmetered air leaks in the process of R&Ring the intake, it would change the required setting as well.

If it just started doing this (and you didn't touch anything recently) one of the most likely causes is vacuum leaks. Especially since you mention the intake was removed. Plenty of opportunities to create or develop a vacuum leak. Another possibility is the gas. Did you recently put gas in?

[SIMid]

If it just started doing this (and you didn't touch anything recently) one of the most likely causes is vacuum leaks. Especially since you mention the intake was removed. Plenty of opportunities to create or develop a vacuum leak.

The joy of tracking this down as I have read so many posts of owners trying to find their leaks. It's like the never ending story. :(


Another possibility is the gas. Did you recently put gas in?

You mean fill up the car with fuel/petrol? If so, yes I did, but not full.

Bad fuel?

[David T]

The joy of tracking this down as I have read so many posts of owners trying to find their leaks. It's like the never ending story. :(



You mean fill up the car with fuel/petrol? If so, yes I did, but not full.

Bad fuel?

Yes. If it was OK and you noticed this -AFTER- you put gas in, bad gas has to be considered as a possibility. Use this gas up as far down as you can and refill with fresh fuel. Maybe the problem will go away?

[A Van]

I had a similar issue once which took me a while to find, until it hesitated then stopped completely.
Poor connections at the ballast resistor.
It was quite a noticeable hesitation

[berickson926]

Does it only seam to happen when the engine is cold, such as within the first several minutes after a cold start-up?

My car has this exact problem. It only happens when I first start driving the car cold. After a few minutes there are zero issues. Vacuum leaks?

[David T]

My car has this exact problem. It only happens when I first start driving the car cold. After a few minutes there are zero issues. Vacuum leaks?

If you only notice hesitation when cold it is probably the Control Pressure Regulator aka warm up regulator or the vacuum hose connections to it. The CPR can go bad or be out of calibration.

[NightFlyer]

My car has this exact problem. It only happens when I first start driving the car cold. After a few minutes there are zero issues. Vacuum leaks?

As David said, more likely than not an issue with the CPR/WUR. Welcome to the club - seems to be a bunch of us currently experiencing an issue with this K-Jet component (myself included). As I know what the problem is and it isn't that big a deal, I'm waiting until winter hibernation to investigate it further and repair it (I'll probably end up rebuilding it).

Best luck :thumbup:

[SIMid]

I had a similar issue once which took me a while to find, until it hesitated then stopped completely.
Poor connections at the ballast resistor.
It was quite a noticeable hesitation

Mine is ever so slight, doesn't stall, just like a small hiccup when I apply the throttle.

I'll check those connections as it will only take a few minutes and see what happens.

[SIMid]

Yes. If it was OK and you noticed this -AFTER- you put gas in, bad gas has to be considered as a possibility. Use this gas up as far down as you can and refill with fresh fuel. Maybe the problem will go away?

It was after. I could put a higher octane next time and that may balance up the issue with the fuel.

[David T]

It was after. I could put a higher octane next time and that may balance up the issue with the fuel.

Higher octane does not necessarily mean better fuel. Try another brand. Maybe the station you bought the fuel in had water in their tank.

[David T]

Mine is ever so slight, doesn't stall, just like a small hiccup when I apply the throttle.

I'll check those connections as it will only take a few minutes and see what happens.

A *slight* hesitation within the first minute of starting the motor is not abnormal. If it gets worse it should be fixed. Realize that even with everything working perfectly the motor is calibrated to run it's best at operating temperature and that can take a few minutes.

[SIMid]

A *slight* hesitation within the first minute of starting the motor is not abnormal. If it gets worse it should be fixed. Realize that even with everything working perfectly the motor is calibrated to run it's best at operating temperature and that can take a few minutes.

It only hesitates when the engine has warmed up. Starts first go, hot or cold. And only hesitates occasionally, not every time I take off.