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CPS dead? I'm in the Denial Stage /w pics

RTicUL8

RTicUL8

NAXJA Forum User
Location
Rocky Mountain High... Colorado!
Got fuel,
Got spark,
Got good voltage,
engine is cranking, but not starting.
and got a good ground to engine block & firewall.
Reseated the CPS cable....nogo!

'88 4.0l

Tested CPS ohms. It fluctuated between 219 to 270.
Here it's 242:
DSCN1606.JPG


Tested CPS AC voltage while cranking - nada!
DSCN1609.JPG


Is it toast?

I saw in a previous posting by Eagle that there is a retrofit kit - part #83100066 that's cheaper than the stock CPS.
 
If you have spark, then your cps should be fine. Give us some history on how this started and what you did before it started.
 
I think I've figured out your problem as has Cherokee89. Your jeep is starved for dirt. Throw a bucket of dirt on it and see if that helps, if not spread some oil around under the hood and some in the air filter.

Hope this has been helpful, remember to keep your XJ happy.
 
I have never seen that scenario.

If you recently cleaned the engine, you could have "hosed" the TPS. If the TPS gives a reading like it is at WOT wide open throttle position, the computer will shut off the injectors. It thinks you are trying to clear a flooded condition.

I would first pull a plug and make sure they aren't wet with gas. If they are, you will need to either replace the plugs or clean them and dry them out. I have seen lots of XJ's that have been flooded that simply would not fire with wet plugs.'
 
According to the Chilton FI manual, anything from 125 to 275 ohms on a hot engine is in spec for the CPS, and as Old Man points out, failed CPS=No spark at all. The very short voltage spike from the CPS in action might be too small and brief to trigger a digital meter

You've got fuel and spark, but is the fuel getting through the injectors? Next suspect might be the cam position sensor inside the distributor, or the wiring to it. That's what sends the signal for injectors.

Either that or the engine is afraid to run for fear of soiling itself.
 
The day before it died, I had just installed an ARB snorkel.
I did pressure wash the engine.
The only wires that I disconnected were the electric fan and temp sensor on the radiator.
I have fuel to the rail, but I did not check the output of the injectors, so perhaps it is not getting fuel to the piston cylinders. I'll check that tonight.
And yes, it might be the TPS too - anyone got a spare one sitting around? ;)
 
Off topic- but the picture is so great I can't refuse.

At the top of the 1st picture there are the 4 blue relays- did those ever come enclosed in something? Mine look exactly like his, and I thought that I was missing a cover?

TIA- PRL

As everyone else said- Kudos on the clean engine!!! Unless you Photoshopped the dirt out!!!!
 
yes there is a cover but it's not an enclosure just sits over the top to hide them from view.
 
I have seen engines that had spark and fuel but wouldn't run because the coil was going and the spark wasn't hot enough. I would test for this by carefully putting a little gas or some ether down the throttle body. You could also use a noid light to test the injector signal.

PS: My '01 isn't that clean!!! I live on a dirt road, so I couldn't keep anything that clean for long.
 
If you recently pressure washed the engine, one step might be to go and unplug, clean, lube and replug every electrical connector you can get your hands on. There might be enough moisture or corrosion in one to kill it. The voltages and signals in this system are pretty wimpy, and easily affected by poor connections. I'd look especially at the coil/distributor end of things, but also at the TPS, which is notorious for being clobbered by pressure washing.

I seem to remember someone who had drowned his TPS reviving it by taking it out and very cautiously baking it dry. Anyone remember this?
 
I was the second owner of the XJ (my dad was the first). I don't ever remember there being a cover over the relays. My '93 and '00 XJs have covers on theirs.

The reason it's so clean is that I recenly rebuilt the engine. I sank it in a BIG puddle on Apex mtn. Colorado.
I had to pull apart the entire engine.
Here's a fugly BEFORE pic: (that's water and silt in the cylinders)
DSCN1003.JPG


It was running fine for about 400 miles after the rebuild.
However, the day after I installed the snorkel, it stopped working.
I did clean the engine before installing the snorkel, and I may have gotten something wet - perhaps the TPS??? Oh well...it keeps sucking up my money.
 
Sparkman said:
I have seen engines that had spark and fuel but wouldn't run because the coil was going and the spark wasn't hot enough....
Click to expand...
I've experienced this too.

Apart from the plugs being wet on the inside of the engine, they could be wet on the outside. Is there water in the plug recesses on the block, wires, coil, distributor?
 
Lou said:
I've experienced this too.

Apart from the plugs being wet on the inside of the engine, they could be wet on the outside. Is there water in the plug recesses on the block, wires, coil, distributor?
Click to expand...

Plug recesses = dry
Wires = dry
Ignition coil = dry
I also checked inside the distributor and it's dry in there too.
I have not pulled the plugs yet.
 
Throw a little gas or ether in it, that will tell you if it's a fuel or spark problem real quick. If it runs, it's a fuel problem, if it doesn't, it's a spark problem. A little WD-40 in the offending connector should dry it out.
 
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