Chevy & GMC Vans

had to drive the van to and from London Sunday (45min away on hwy) and again on Monday. had noticed it hesitating a bit and surging on Saturday evening around town. it did it again on Sunday a few times. scared it was going to leave me stranded .. again.

i went to work and grabbed an AC Delco cap and rotor and already had a bottle of the GM 'fuel injection treatment plus' aka poppet cleaner.

Monday morning changed the cap and rotor, dumped in the bottle of cleaner and filled it from 1/4 tank to just over 3/4 with gas before departing.

still hesitating and shuddering a bit .. Jen suggested to give the cleaner a day or two to work

note: AC Delco cap and rotor were installed June 13/08 ... so 1yr and 1mth ago

starting to get frustrated that this 99 runs smooth but has the power of a turd

How is the coil and wires? This is similar to what I have had, although with me it is only when wet or very humid. Then it is a virtual fireworks show around the coil.

How is your CMP retard?
Have you cleaned your MAF sensor lately?

v8famvan wrote:How is your CMP retard?

Thats not a nice thing to call him James...LMAO, sorry couldn't let that pass by.

On a more serious note, how well is that "GM 'fuel injection treatment plus' aka poppet cleaner" supposed to work James/Rob?

a year ago: the cap/rotor and poppet cleaner worked for me. better than seafoam. solved the problem.

and ya.. that's nothing to call me James.. LOL

i have no idea what CMP retard is

as for the coil, it was done a couple of months ago, replaced with a delco when mine died instantly one day on a road trip

MAF cleaning: I have not, yet, guess I'm doing that one tonight lol

How does one clean the MAF sensor? I'm lost on the 'retard' one too ;)

Don't forget to check the little screen vent in the bottom of the distributor, they can clog up and I've heard that the cap needs to be vented or the build up of ozone can cause problems. Some replacement distrubutors have too tight of a screen and don't vent well. I've never seen it, but I've heard of it a couple of times.

start with the simple stuff first, pull each of the plug wires off, both ends and the coil wire.
my recent experience has been a plug wire on the no. 6 cylinder that fell off in my hand, and a wire on the dist cap that came off with two fingers, crimped the metal connector with a pair of pliers.
If the metal connectors aren't making positive contact on your wires, the spark has to jump the gap in the dist cap, the bad connection then the electrodes on the plug. It works your coil to death.

astrozam wrote:

v8famvan wrote:How is your CMP retard?

Thats not a nice thing to call him James...LMAO, sorry couldn't let that pass by.

After looking at my post, I saw how it looked.... ](*,) LOL.

Let me relate a litte storyfrom last week....

A '99 Safari van comes into the shop with a complaint of rough run. I hear that the owner has been to multiple other shops trying to get the vehicle to run good. Maintenance/tune-up work has been done by the other shops with unknown quailty of parts.
Within 5 seconds of starting the vehicle up, I diagnosed a bad engine mount. Within 1 minute of scanning it I had diagnosed a CMP retard issue. (it was at - 15 degrees, spec is 0 +/- 2) Then, I drove the vehicle. Found the vehicle had a lack of power & checked the data on the scan tool. Found the mass airflow sensor was reading low. Quoted on the repairs & then did them.
1. Replaced the bad engine mount, $25 for part.
2. Adjusted the CMP retard, $0 for parts.
3, Cleaned the MAF sensor, $0 for parts.
Customer could not believe how much better the vehicle ran & felt.

My points are:
Sometimes the best repairs don't require expensive parts.
Never underestimate the value of a good mechanic.

That being said, I offer my advice on the problem you have....

astrozam wrote:On a more serious note, how well is that "GM 'fuel injection treatment plus' aka poppet cleaner" supposed to work James/Rob?

Zam, that "GM 'fuel injection treatment plus' aka poppet cleaner" works very well. Nothing else works quite like it, so my customers say.

v8famvan wrote: retard?

Haha James,I guess all that Tech talk has finally got to ya : )
Just kiddin'

Thanks for the info James

having no clue what CMP retard is .. I googled it.. seems we need a very expensive fancy scanner to check/adjust CMP retard. that means take it to a shop. $120/hr for diag time and the possibility of requiring a new cam position sensor to the tune of around $35. I'm sure the shops around here will also charge at least an hour to replace or adjust.

below is what I found.. even if you don't throw a code (which I didn't) if can be out it seems. It also tells me that even if I spend the $35 and change the part myself, it could very well still be out of adjustment and run exactly the same. sounds like i'm fooked :-k


Circuit Description
This diagnostic trouble code (DTC) monitors the crankshaft position (CKP) and the camshaft position (CMP) signals to determine if they are synchronized. If both signals are not observed by the control module within a narrow time window, the vehicle control module (VCM) will determine that an error has occurred.

Conditions for Running the DTC
The engine is running

Conditions for Setting the DTC
When the engine is running, the cam sensor reference pulse is not detected at the correct position relative to the crankshaft position sensor pulse.

Action Taken When the DTC Sets
The control module illuminates the malfunction indicator lamp (MIL) the first time the diagnostic runs and fails.
The control module will set the DTC and records the operating conditions at the time the diagnostic fails. The control module stores the failure information in the scan tools Freeze Frame/Failure Records.
Conditions for Clearing the MIL or DTC
The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.
A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
Use a scan tool in order to clear the DTCs.
Diagnostic Aids
Check the following items:

A loose CMP sensor causing a variance in the sensor signal
Excessive free play in the timing chain and gear assembly
Incorrectly installed distributor - 1 tooth off in either advance or retard positions
A loose distributor rotor on the distributor shaft
A loose or missing distributor hold down bolt
An intermittent may be caused by any of the following conditions:

A poor connection
Rubbed through wire insulation
A broken wire inside the insulation
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.

If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.

1. Perform the Camshaft Retard Offset test procedure as follows:

Install the scan tool.
Start the engine.

Important
The camshaft retard reading will not be accurate below 1000 RPM.


Raise the engine speed to the first specified value.
Monitor the camshaft retard with the scan tool.
Is the camshaft retard reading within the second specified value?
+2° / -2° @ 1000rpm

2. Note the camshaft retard reading from the previous step.
Raise the engine speed to the first specified value.
Does the camshaft retard reading change more than the second specified value?
+2° @ 2000rpm

3. If the distributor is one tooth off in either the advanced or retard positions the vehicle may run but 0 degrees camshaft retard offset will not be obtained.

4. Perform the Camshaft Retard Offset adjustment procedure as follows:

With the engine OFF slightly loosen the distributor hold down bolt.
Start the engine and raise the engine speed to 1000 RPM.
Using the scan tool monitor the camshaft retard offset.
Rotate the distributor as follows:
To compensate for a negative reading rotate the distributor in the counterclockwise direction.
To compensate for a positive reading rotate the distributor in the clockwise direction.
Repeat step 4 until 0 degrees offset is obtained.
When 0 degrees has been obtained turn OFF the ignition and tighten the distributor hold down bolt.
Did you obtain 0 degrees camshaft retard?