1989 XJS with marelli ignition.

Got it running (thanks forum!), now starts easily and idles smooth but bogs with gas.
new plugs, wires, rotor, cap, new gas, new fuel filter, fuel pressure is 35-37 psi,

TPS voltage is .30 it and 4.6 WOT.

What to check next?

 

So! I swapped the fuel injection ECU in trunk and now revs but is running rich and revs slowly.

ideas?

 

are the 02s in good nick?

 

Solved!!

Curse of the previous owner. A lone ground wire (near coils) was cut and not connected.

 

I've got a 1990 XJS Coupe V12.


BACKGROUND:
Replaced the plug wires, rotor, cap, all vacuum hoses (even checked the little red on going to cabin), and replaced the temp sensor on the "B" side intake manifold. Also, checked gap on both throttle bodies and they are within spec, I haven't changed injector wires out, and I think it's running rich.


I have a Jag shop manual, parts manual, and Kirby Book, but no help.


QUESTION:
Here's the issue, when I fire it up I get a little bit of rough idle, and if I rev it with no load it runs just fine, the second I put it under load and give it gas, I get backfiring (sounds like at the "A" side manifold.)


I know my way around Jags (have a few) but this one is stumping me.


I would greatly appreciate feedback.


PS I've done all the simple things like clean the injectors, replaced the fuel, and the fuel lines in the rear of the trunk are all newer.

 

Go find my recent thread, same thing just happened to mine. Fine in "P" or "N" no go under a load, pinging, missing, running rich. Mine turned out to be the CTS connection.

 

I bumped it up for you to read. I was surprised that's what did the trick for mine but it's been running great ever since.

 

I replaced the CTS, but how do you test the wiring? Is there a set resistance or voltage it should show?

 

there is set OHM's the CTS should show at different temperature. I'd suggest pulling the CTS plug, checking the OHMs then plug it back in, pull the plug on the ECU and check the value on the two connectors from the CTS on the ECU plug.....only thing is I'm unsure which two on the ECU plug.

 

JTsmks, thank you for making the video on the CTS. I've ordered the replacement connectors, and I'm going to replace all the fuel injector connectors as well. Again thanks, and good job.

 

Oh, I didn't make that video, I simply copied and pasted the link. Hope you resolve your problem soon.