So much fun chasing ghost on these cars..

So I have this '98 X308 NA with tthe AJ26 engine. Long story short, I now have two TBs for it. Both are the updated part with the sticker. One came with the car, When it's normal it delivers performance and smooth idle as expected, but once after a while (always after engine warmed up and driven for some time though) it will act up. Idle all of a sudden becomes erratic, usually stays high, above 1200rpm or even surging towards 2000rpm, or drop to below 500rpm and almost stall. You can imagine that happening when you are in rush hour traffic. And then next day it will be fine again. The other TB was purchased from SNG Barratt as a cheap rebuilt unit at $250 as a result of this. This one behaves will as it does not act up, but it delivers inadequate performance. I checked with an OBD 2 App. and full throttle revealed only 69-73%, whereas the old one reads 100% at full throttle. I am thinking about making one good TB out of these two guys, but seems everyone says the TPS can not be swapped on these TBs, as they will require equipment re-calibration afterwards?

p.s. new fuel pump, new MAF.

Anyone?

Paul

 

How are the ignition coils? And the engine speed sensor (rear of the engine)?

I changed my rear sensor, as the car started to 'stutter' a little on idle. Changed, problem gone. But it can also be faulty lambda sonds (O2 sensors). Check if you can what Signals they are putting out...

 

This sounds like a ill adjusted TPS or perhaps a throttle cable issue, but I'm leaning toward the TPS first.
Read this starting on page 5.3 down to 5.12, it details the throttle body and measurements. http://www.jagrepair.com/images/Trai...ual-9-5-01.pdf
To adjust your throttle cable, check this, I believe yours is the same adjustment...I wouldn't be as free wheeling with the adjustment as he was though.

 

Dear High Horse! I am so glad to read your input after I've successfully solved the problem on my NA '98!! It was indeed as simple as throttle cable adjustment for the new TB! It just never occurred to me that the two TBs apparently have different preset angle! However with my '00 XJR I did not have such luck. As I discovered this issue I went on to check the slack on my XJR, and was loose, too! OBD reads only 73% at full throttle! I then tighten the cable to the extreme fitness, yet it still only gives 79% at WOT, so now I'm gonna look into the information you shared above..