1993 Buick Regal 3.8 rough running

[tinner105]

My friend has a 93 regal 3.8 when he got it the 1-4 coil pack was bad.
We replaced it it runs better but still not like it should.
When you accelerate it really stumbles badly then straighten out.
the guy he got it from said he had these codes then erased them.
#21
#23
#42

he cleared them

we ran it fo 30 miles and got no codes so i have no idea where to start.

Thanks for the help

Tinner

[Tech II]

Codes are for the TPS and IAT sensors......42 is for EST(electronic spark timing)......

More often than not, code 42 is the ICM, the ECM, or the wiring in between....

last tuneup? Check spark output of all 6 coil terminals....

[tinner105]

I checked the TPS it had 4.55 volts
and the other two legs was close to voltage and it raised an lowered as the throttle was opened/closed
The IAT was OK it ohmed out within limits.

It just had new plugs installed.

How do i check spark on the coils.
measure it or make sure its there?

Do you know of any problems caused by the curise control?
The guys dad had it disconnected and he connected it.
I disconnected it again just in case there was a problem with it, that might cause some of these problems.

Thanks for the help BTW

Tinner

[tinner105]

I've been scouring the net and found alot of Porn
But i also found some usefull info too.
I have a hunch thats the cats/cat are clogged.
because its not throwing any more codes after we drove it for 30 miles and its was running crappy several times during.

what do you think

I will try and check it tomorrow.

[HotZ28]

How do i check spark on the coils. measure it or make sure its there?

A good inline spark tester when set @ .200 should show if the coils are putting out a good blue spark.

Do you know of any problems caused by the curise control?
The guys dad had it disconnected and he connected it.
I disconnected it again just in case there was a problem with it, that might cause some of these problems.

Cruise control has nothing to do with spark.

its not throwing any more codes after we drove it for 30 miles and its was running crappy several times during.

Most of the time, it takes more than 30 driving miles to go through all the engine operating parameters before setting codes.

[tinner105]

Thanks
We going to dig into it today.
He drove it home and maybe we will have some codes today.

I really like digging into a problem like this.
I know we will figure it out.
Just have to start from square one....



regarding the cruise control... I thought it might be stealing vacuum away from the engine because of a malfunction or something. It was disconnected before and we didn't know if it was done for a reason or they just didn't want a 85yo having cruise control

Thanks for the help its appreciated.

Tinner

[HotZ28]

You may be able to find one of these @ your local NAPA, or O'Reilly parts store. The Lisle Part # 50850 is shown to be in stock at my local O'Reilly.

Quickly Checks Spark at Plug Wire. A handy tool to check ignition spark without removing the spark plug. The tool is specially calibrated to measure ignition voltage. Works on both standard and electronic ignition systems. Easy to use. Simply adjust calibration screw to proper gap size. Attach spark plug wire to end of tester. Clamp tester on engine to ground. Crank engine and check for spark.

Lisle Ignition Spark Tester With Adjustable Gap

Order No. LIS50850

List Price: $7.46
Price: $5.70
http://www.thetoolwarehouse.net/p-7200-thexton-404.aspx




Thextron Ignition Spark Tester With Adjustable Gap

Order No. THE404

List Price: $20.94
Price: $10.85
http://www.thetoolwarehouse.net/p-7200-thexton-404.aspx

[tinner105]

Thanks

Here's the latest

Chacked the spark on every plug and it made it accross the gap with a nice pop snap sound.

Checked the fuel pressure it was OK and there was no miminal bleen down.

we did find a bolt missing on a bracket under the abs unit dorvers side.
It went to a bracket on the tranny housing that had a cable coming from it to the throttle body.
Throttle kick down for the tranny i suspect.

Added the fuel dryer the other day and it really does seem to be running alot better.....
but i can still feel the surging a little still so theres still somthing wrong.
Were changing the plug wires and we will run it aroubnd some more and see if it straightens out.
I think next time we will put some preemo gas in it as well.

tinner

thanks for the help.

[HotZ28]

Thanks for the update. BTW, what is a "fuel dryer" & "preemo gas"

[tinner105]

Fuel dryer...is that red stuff you put in your tank to treat old gas.
preemo.... premium gas

And BTW it runs alot better but still lurches some times.

And i got my figures wrong for the fuel pressure....

it measured less than 40 psi i think around 38psi

and the book said 40- 45 psi do you think thats a big problem?

We are also going to change the fuel filter..... who knows if it has ever been changed.
I will check the pressure after we change it and see... who knows it could be clogged a wee bit.

This car is my sons best friend.
His first car too.
I helped him buy it knowing we would be able to figure out what was wrong.
It starts right up, you can hit the throttle and it sounds good.
it just seems to have the problem under a load.
which i guess could be from the lower than optimum fuel pressure.

Ok tomorrow we are heading to the pick a part yard.
We went over the entire car and nave a shopping list of all the little piecec he needs.
One thing about S Calif man do we have some good yards.
And the carne asada tacos from the Taco truck out side it are awesum.

Thanks for all of the help.

Let me know what you think about the pressure.

OH one thing when we had the pressure gauge on it.
after we shut the car off the pressure actually went up....
what do you think of that?

Thanks
tinner

[HotZ28]

Thanks for the clarification of "fuel dryer" & "preemo".

fuel pressure....

it measured less than 40 psi i think around 38psi

and the book said 40- 45 psi do you think thats a big problem?

No, you should try the filter first to see if pressure will increase; however 38-40 psi should not be a big problem.

Click Here for a good article of fuel system pressure checks.

[tinner105]

Fuel filter took care of the remaining surging problem.
When i changed it, the line going to the engine leaked little gas.
( we ran it with the relay out before changing it)
Then when i disconnecterd the tank side.... there was alot of gas. So it was obvious that the filter was restricting the flow. Who knows it could have been the filter it came with new...
Anyway no surging at all now.
I just have to have Joe drive it around a bit to build up a record/data on the computer or the smog machine wont let it test.

Thanks for all of the help/advice it's appreciated.
Now we just have to sort out the dash lights and the signals....

THANKS

Tinner