I'm sure this might be redundant but i was hoping i can get some help regardless.

My 1998 XJ8L is having acceleration issues. Its sporadic. Press the pedal, delay, then kicks in or catches up, then will surge back and forth at all speeds. Kind of like its not getting fuel, then getting a surge of fuel, then none again, repeat repeat repeat. Sometimes it stops, but its been a consistent problem for a month now. I was thinking its the throttle body because the issue seems similar to something that i had a while back. Any thoughts? Also, does anyone know a good place to get a refurbished throttle body or a place where I can send my spare TB to be sent out to be rebuilt? Appreciate any help. Thanks

 

ASI is a common name thrown about, I believe they are in Tenn. Go to YouTube and look them up there (ASI throttle body repair), they describe TB issues and what they do to fix'em.

 

https://www.autoecu.com/throttle-body/

 

From your signature it looks like you have a 1998 VDP and a 1998 XJ8L so why not just swap throttle assys and see if the fault follows the part???

bob

 

Just a thought, it may not be the throttle body at all. Give your MAF sensor a clean, or replace it. It can cause similar symptoms if it's not working properly

 

+1, I went through that w/ my previous X308 it was a gummy MAF.

 

The one on the xj8 is from the vdp. The vdp is basically inop now. I bought it for a $1000 from a dealer. The body was in rough shape.

 

Thanks guys. I'll try the MAF sensor, I have a used spare I can swap out and test. Also, thanks for the TB links.

 

I bet the bearings inside are seized up. I did a write up on my 98' XJR's throttle body a few years back. I think it was titled:
"1998 XJR throttle body" if you do a search.

 

I agree.
Try replacing the MAF on the car. Don't clean it, replace it.
They are NOT expensive.

If you are looking for a TB, I have an extra one that you could send out and have rebuilt. PM me if interested.

But, I would try the MAF first. If not cleaned properly, you WILL damage the MAF. That is why I suggest buying a new one. It can't hurt.

BTW, it is a good idea to do a hard reset when you change the MAF.

 

I cleaned the current MAF sensor, and then replaced with a used spare that I had. No changes. Bummer too, because that would have been an easy fix. Someone told me that they think it could be a bad ignition coil, but I’m still leaning to throttle body. Would I get a light if a coil went bad?

 

If it was a coil, it would be throwing numerous codes. Misfire/Voltage/Restricted Performance.............

When the hesitation occurs, is the car bogging down, or just taking time to realize your pressing the accel pedal? If it's bogging down, then it is a sensor more than likely. If it just takes a second for the TB to realize your pressing the accel pedal, then it's the TB cable.

Check the TB accel cable. Make sure it is attached with very little play. (there should be some, but it shouldn't be loose)
The plastic retention pulley that holds the accel cable onto the TB can sometimes crack. This will cause "play" in the cable. Hence a hesitation before the cable tightens up and pulls on the TB. If this is cracked, or has too much play, then you found your problem.

I would put a new MAF in the system. Everything your describing points to the MAF or O2 sensors. The MAF is a VERY delicate device. It can be damaged VERY easily, especially when old or cleaning it. If you do not wait for it to "cool off' and try and clean it, you will ruin the MAF. Also, it must be fully dry before re-installing.

Do you have a scanner?
Can you check the O2 sensors on the car.
Check the upstream O2 sensors. (Before the cat)
Check the MAF flow rate.

These sensors tell the ECU how much, or how little fuel to put into the engine. This would be the result of the engine bogging down.

If your not throwing any codes, that's a good thing.

 

If you haven't done it yet, clean the throttle bore and plate and check the tension on the accelerator cable. I had the same problem on my last one when I bought it in April 13. Cleaning the throttle and MAF fixed the issue.

 

Awesome info! thanks guys. Time to get back to it, and try some of these ideas.