xj starts idles down and shuts off

mossyOblack

Member
Joined
Nov 20, 2012
Location
hickory/newton
Ok just swapped motor into my xj... Motor was from a 92 and I put out in my 98...
Took all electroNics from the 98 and put on the 92.. Pretty much all accessories/intake manifold/all sensors..

When starting it starts runs for a few seconds (like 3) then dies...unless I keep my foot on the gas.. But even then it runs rough.. Misses and skips and back fires Smells really rich blue smoke.. Some black..

ok here is what we have done so far... We changed the wiring harness because the previous
One had been hacked on and had the injectors str8 wired for some odd reason.. We did this because it seemed like it was getting more fuel than needed and wasn't comfortable knowing the wires were rigged like that...

No luck..

Changed plugs and wires.. All plugs were burning evenly except # 6 it was soaked in raw fuel...
(Ok this has me curious because the previous motor had the #6 piston to explode).. So is it possible that the #6 injector is bad? Maybe stuck open? Dumping fuel

I haven't checked to see if #6 is getting fire yet but I will today.. But what would cause that one cylinder to not fire?

Any helpful diagnostic, opinions will be greatly appreciated if it pertains to the issues at hand thank you..

May post a video later
 
Check the vaccum line going from the intake manifold to the MAP sensor. Bet someone for got to hook it back up after the motor swap.
 
mossyOblack said:
Wouldn't I throw a code?
Click to expand...
you would think, but not always. Even if the vacuum line looks connected, disconnect it, see if it makes a difference. I've seen it where just wiggling the vacuum line connection a the MAP sensor will change engine idle drastically; replace it with some brand new bulk rubber line.
 
Ok today I unplugged the idle air control sensor and the car idles without shutting off.. It idles high and rough.. But won't rev past 2500 rpm... Seems like limp mode... So with the sensor plugged in it won't idle... Unplugged it idles but in what I think is limp mode
 
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