Well ...On the weekend, I took off the battery to give it a really good charge (temps are predicted to go pretty low this week) and after I refitted it, the old bus (which normally runs quite well) suddenly developed a stumble at idle ...enough of a stumble to get the engine to stall at the occasional traffic light ....Not Acceptable!
Actually, I'd noticed a slight hesitation over the last couple of weeks and figured it was probably overdue for some intake maintenance -- but what with it being winter and nowhere warm to work ...well, of course I put it off.

But stalling at lights was the final straw, so today I resolved to get it done. Donning my down vest and toque, picked up a nice new WIX airfilter and equipped with shop towels, contact cleaner, degreaser, carb and MAF cleaner, took apart the intake.

As expected, the brown soup was there alright.




Anyway, cleaned the muck out of the pleats, washed all the hoses out, fitted the new airfilter, sprayed all the sensor connections w/contact cleaner, gave the maf a blast of maf cleaner, cleaned the muck out of the butterfly and put it all back together. Result?

Running like a clock, no more stumble, just like new.

Took her for a test drive up to the lake ..even though fishing was rather slow, managed to bring home a nice rainbow for supper ...so a good day all round ...except the sore back from all that leaning over ...Oh well, was worth it!

Larry

 

An excellent reminder to all of us, Larry!

And thanks for the photo that provides visual proof of the problem all XJ40s suffer. Even though I've seen it many times before on my own cars, I still wish I could unsee it! It's gross!

Cheers,

Don

 

I have a similar stumbling.. 91 Sovereign. At 750 rpm idle, engine is calm and quiet, sometimes undetectable vibration.... But when warm, right At 1000 rpm engine stumbles (rarely stalls out, but it will eventually worsen to this, I reckon). Above 1000 rpm just fine.

I keep putting off the MAF and Throttle Body cleaning and maintenance, but I need to get it done. So what is that nasty goop? I will probably see the same thing when I pull it apart.

 

Hi Jagbro,

That goop is an accumulation of dirty engine oil drawn up through the crankcase breather system and deposited in the air intake ahead of the throttle body. What doesn't get inhaled into the engine and burned in the combustion chambers tends to cling to the walls of the breather hoses, intake elbow and accordion hose just ahead of the throttle body. As it accumulates it drains down to the bottom of the accordion hose and throttle body, where it leaks down the butterfly valve shaft into the throttle position sensor (TPS). It also makes its way into the bottom of the intake manifold where it helps gunk up the port for the EGR and carbon canister purge systems. This is why periodic cleaning of the air intake, breather hoses, throttle, TPS and EGR port are so important on an XJ40.

Cheers,

Don

 

Thanks Larry, I had similar symptoms in the Moneyfunnel this week. I was sure I had got some bad gas, but as you said of yours, I was 1/2 through the tank before it started. I "stumbled" across this thread while looking for the code clearing sequence for a ff89 code on the Other car. I took the intake apart and cleaned it all up and all seems well. By the way, I found that I had left the air box to Air Injection pump hose off last time I was in there. I think this may have contributed to this condition of "excessive intake caramel."

 

I have added an oil catch can to combat this issue. I think it works the hose end at the intake elbow is as clean as the day I bought it.

You will have to empty out the can periodically.

 

Could we get a photo of this please? I am having trouble imagining it.

 

 

Really! I was thinking it might be a tad bit more complex than that....