acceleration flat spot

I have experienced a flat spot (delay) in acceleration especially in first gear. I have a five speed manual tranny. This does not happen on cold winter mornings when I suspect the auto choke is engaged.
This happened on both my 2001 and now my 2004 Jimmy 2dr.
The dealer cannot find a problem or solution nor are there any codes for this. In addition, they cannot tell me how to take my shift knob off the shifter so I can put on my choice of shift knob. Any solutions out there?

I have experienced a flat spot (delay) in acceleration especially in first gear. I have a five speed manual tranny. This does not happen on cold winter mornings when I suspect the auto choke is engaged.
This happened on both my 2001 and now my 2004 Jimmy 2dr.
The dealer cannot find a problem or solution nor are there any codes for this. In addition, they cannot tell me how to take my shift knob off the shifter so I can put on my choice of shift knob. Any solutions out there?

Take it back to the dealer and have them hook up the Tech 2 and take it for a drive so they can log the sensor values when this problem happens.

Don't take the "we don't know what is going wrong bullshit."

They are just trying to avoid warranty work.

Take it back to the dealer and have them hook up the Tech 2 and take it for a drive so they can log the sensor values when this problem happens.

Don't take the "we don't know what is going wrong bullshit."

They are just trying to avoid warranty work.


Many thanks! I will ask for the Tech 2 next month.
I will let you know how it turns out..

Do this ASAP, don't wait or they will stop helping you.

Do this ASAP, don't wait or they will stop helping you.
Dealer did my 20,000 km oil change and required checks, and insist that there are no codes appearing for my problem. They say Tech 2 has been around for years and has been upgrade since inception. Still have my problem but not as bad now that the cold is here. Seems to accelerate better the colder it is. Thanks for your reply.

So they didn't hook it up and log the data?

So they didn't hook it up and log the data?
Would they not have done that to to see if code problems appear?

I am not talking about checking the codes, I am talking about logging the sensor values when driving to see if there is a sensor that is slow or something.

I've got a flat spot too on my 93 jimmy but it has 163k on it. I'm wondering if it needs an intake rebuild? New jets maybe?

ALSO EPROMS? Are there any good EPROMS that improve reliability?

I've got a flat spot too on my 93 jimmy but it has 163k on it. I'm wondering if it needs an intake rebuild? New jets maybe?

ALSO EPROMS? Are there any good EPROMS that improve reliability?


What are EPROMS ?

I've got a flat spot too on my 93 jimmy but it has 163k on it. I'm wondering if it needs an intake rebuild? New jets maybe?

ALSO EPROMS? Are there any good EPROMS that improve reliability?

What kind of injection system do you have, CPI or TBI?

What kind of injection system do you have, CPI or TBI?

I don't know.
How would I go about getting it?

Do you have the vortec plate on the top of your engine?

Do you have the vortec plate on the top of your engine?

In my youth I could rebuild 4bbl carbs no problem, but I had no time when the kids came so I am out of the loop. Computers in cars now take the fun out. Our silly government went metric while I remain in mph.
I have an '04 Jimmy 2dr 4x4 with a manual tranny 6 spd. Documents say a Vortec 6 cyl engine.
What specifically should I look for to identify what you need?
Would increasing the octane of gas make a difference? Manual says to use regular.

What kind of injection system do you have, CPI or TBI?


TBI.......and the weird thing is it runs ok when cold but when its warm it has no power, will hardly maintain speed on the highway, feels like it's "missing" and even seems to semi-backfire through the intake.

I took it to the GM dealer and Firestone 3 times in the past 3 weeks and they replaced the catalytic converter and distributor but there is not any difference at all.

I did a tune-up on it replacing plugs, wires, cap and rotor but nothing seems to help.

You mentioned a TECH 2 analyzer. Are those or something like them still made and if so where could I get one and for how much? I've spent $1500 on this thing in the last 3 weeks and I'm about ready to get something else but I really like Jimmy/Blazers and would rather keep this one if I can get this one running.

Sounds like your timing is out.

Disconnect the beige and brown timing wire from the PCM and time your truck with a timing gun to base zero timing and then reconnect the wire, clear the computer and you should be good to go.

Sounds like your timing is out.

Disconnect the beige and brown timing wire from the PCM and time your truck with a timing gun to base zero timing and then reconnect the wire, clear the computer and you should be good to go.


I really appreciate your help and I'm sorry to be so ignorant but what is a "PCM"? I'm familiar with the ECM but not the PCM.

ALSO have you used the DIGIMOTO and if so what's you opinion?

http://www.digimoto.com/faq.htm

thanks

PCM is the computer which is mounted under your glove box in the passenger compartment.

No, I have not used the digimoto, but I have done research on it. Seems an ok product.

At what RPM is your flat spot. If around 1800 rpm it could be the EGR system. I had this problem and had to unbolt the TBI and clean out the crud in the passage ways.
Bob Shaw