Please Help Driveability Problem

[Isaac-1]

I have been having some drivability problems on cooler (below 40 degrees) mornings lately until the car warms up, and am not sure where to look for the problem. I have been noticing major hesitation when I put my foot on the accelerator (about .5-1 second delay, its like the engine bogs down for a second then surges forward). Also about half the time in the morning my console gauges are doing the full sweet like after a computer reset, I suspect I am getting a voltage drop upon cranking that my battery may be starting to go out as it is now 5 years old, I am not sure if this is related to the other issue, as the hesitaion happens regardless of the needle sweep. Since this only started with the cooler weather I am not sure if any of my mods are to blame, or if this is some other sort of problem (my mods are listed in the sig below).

Thanks for any help Ike

 

[Dan_Soprano]

I have been having some drivability problems on cooler (below 40 degrees) mornings lately until the car warms up, and am not sure where to look for the problem. I have been noticing major hesitation when I put my foot on the accelerator (about .5-1 second delay, its like the engine bogs down for a second then surges forward). Also about half the time in the morning my console gauges are doing the full sweet like after a computer reset, I suspect I am getting a voltage drop upon cranking that my battery may be starting to go out as it is now 5 years old, I am not sure if this is related to the other issue, as the hesitaion happens regardless of the needle sweep. Since this only started with the cooler weather I am not sure if any of my mods are to blame, or if this is some other sort of problem (my mods are listed in the sig below).

Thanks for any help Ike

stupid question, did you install a chip to correct the a/f curves after changing the MAF??

 

[Isaac-1]

The Pro-M came calibrated for 19lb injectors, therefore I assumed no chip change was needed.

Ike

 

[medik13]

Do you have the MAF in the fenderwell or a 90* bend before it? How long has it been before you started having issues? What did you install right before you starting having these problems?

 

[Isaac-1]

The MAF currently is mounted with an exposed filter in the same location as the stock unit. The problem started when with the cold weather a few weeks ago, not after any particular mod (at least 1 month after the last engine related mod I installed, perhaps 2-3 weeks after having the cluctch changed and having an Aluminum driveshaft installed)

Ike

 

[wms004]

The Pro-M came calibrated for 19lb injectors, therefore I assumed no chip change was needed.

Ike

a chip will correct ratios when dynotuned.. and the pro-m is supposed to be one of the easiest to work with according to my Autologic tuner

 

[Isaac-1]

I am thinking about buying an OBDII scanner with Palm interface that would allow monitoring of fuel trim, etc. to see it anything is going wacky when the car is hesistating. Does anyone think this will show anything useful (fuel trim, etc.) considering no warning lights are coming on?

Ike

 

[nyuk98gt]

Isaac-1:

I'll bet your battery is the culprit. I know that Louisiana doesn't get 5' of snow but the mornings can be pretty crisp. A 5 year old battery (particularly in a hot climate) is almost a candidate for the Guinness Book.

You can have the battery load tested, too, to convince yourself that it needs to be replaced.

How old is your fuel filter?

You may have water in your gas, too. If the tank is low and the weather is cooler than normal, water can condense (and stay in the liquid phase). A can of 'gas line antifreeze' (methanol, I think) will help to move the water out of the tank. In cold weather, you ought to keep your gas tank above half-full.

 

[downsouthman1]

Maybe; just maybe

The MAF currently is mounted with an exposed filter in the same location as the stock unit. The problem started when with the cold weather a few weeks ago, not after any particular mod (at least 1 month after the last engine related mod I installed, perhaps 2-3 weeks after having the cluctch changed and having an Aluminum driveshaft installed)

Ike

I noticed that you said the problem may've began 2-3 weeks after having the clutch changed. To the King Cobra I'm assuming. It mind sound stupid & low-tech but it's possible that the clutch is just now fully seeding & I know that the King Cobra is really stiff in comparison to the stock clutch so it may be that you just need to apply more pressure to the gas or keep more applied to the clutch when getting into the gas. Am I off?

 

[Isaac-1]

Here a answers to the questions asked in the last couple of messages:

I plan to change the battery, but I am not sure how it would effect the car after it is running when there had not been a needle sweep/computer reset.

The fuel filter was changed last summer

I don't think its a water in the fuel tank issue, as my car is a daily driver and average about 40-50 miles per day

On the clutch issue, I am fairly certain this is not it, the car can be idling along with the clutch all the way out at 10-15 MPH in 1st and if I hit the gas it just bogs down for a second or so before surging forward.

thanks for all the comments so far
Ike

p.s. I just ordered an OBD II scanner so I will have that to do some testing with soon I hope

 

[skrow03GT]

I am having the exact same problem with my GT. It started with the cold weather, in the mornings. I am very interested to find out why this is happening.

 

[Isaac-1]

I am having the exact same problem with my GT. It started with the cold weather, in the mornings. I am very interested to find out why this is happening.

That is interesting since we seem to have very few mods in common, maybe its an actual engine problem that is not mod related. Perhaps I can find out more about whats really going on (or at least what the car thinks is going on) when the OBD II scanner I ordered yesterday comes in (its a Palm/Laptop version that supports data logging).

Ike

on another note, we had another cold night here last night with the lows around freezing, I had the needle sweet again today, but no real hesitaion. If I get off from work in time tonight, I will pick up a new battery and see if that fixes the needle sweep on morning startup

 

[Mr Plow]

This may sound dumb but in my stang when i use 93 gas sometimes i get those same problems. When i go to 87 it doesnt have the problem.

 

[1fast03pony]

Ike,

You already know that I also have the needle sweep problem. My battery is only 5 months old. Maybe my battery is bad too? The sweep problem has just come up since the weather got cold. My car is garaged though, and its not that cold in the garage. Im not sure what to conclude?

My only mods are removed air silencer, tri ax, and magnapacks.

It seems that Im not the only one with the sweep problem. It may be an issue thats not mod related, like you said. Im gonna have it checked out by ford next week and ill let you know whats up.

-Jon

 

[1fast03pony]

TTT for more opinions

 

[skrow03GT]

I notice mine doing it when the car is cold, its cold outside, and I drive it without warming it up at all. It will hesitate for ~.5 sec. I notice it when I shift gears, it hesitates even more if im getting on it.


It feels like the engine is either getting too much fuel for that split second, or *gulp* not enough fuel. Please keep us updated on what you find.

BTW- I use 89 octane fuel (stock timing)

 

[skrow03GT]

bump

 

[Isaac-1]

My OBD-II scanner is in, I hope to start logging the activity on our next cold morning.

Ike

 

[skrow03GT]

soo, any updates?

 

[GTblack_00]

Well, here is some info, I have a 2k GT and with the factory motor my car did this also, got the new motor, still did it. My solution was to critique the MAF transfer and also bring on enrichment all the way to 120*. There is still a small delay apparent a very small percentage of the time. My theory come to mind that with temperature changes the sensors have different resistance and I will as soon as I can log the TPS sensor info at different temperatures to see if tps changes reading untill the temperature warms up around it... Untill then I have my fuel_ect_multiplier function enriched when cold and that solved my problems even after tuning MAF transfer correctly. I seem to find this is a common problem around mustangs. All mustangs I have ever driven have done this, it is probably part of the tune.