Hi.
After removing the intake manifold to replace a leaking throttle body hose, This 2002.5 V8 has no spark or compression. Car was running 100% when garaged. I've put my Delphi scanner tool on the car and don't have any codes showing up. I've disconnected and reconnected every plug that was detached prior to manifold removal. Battery voltage 12.6v Any ideas?

Thanks.
Kevin

 

How did you determine the lack of compression? Did you do use a mechanical gauge on all cylinders? I could see something such as accidentally unseating a connector that would take out all spark, but am having a hard time understanding how one could lose compression in 8 cylinders.

 

What about bore wash? Did you start the car to move it then stop it shortly after?

 

Hi Carl.... Engine turns over as if there is no compression. sounds like all spark plugs have been removed without the pressure.

 

Hi Norri.
No. Only tried to start up after intake was reinstalled. I tried the oil trick for bore wash, it made no difference.

 

I would go back and double check all of your intake work. No air coming in means nothing to compress. At the very least do a physical comp check as Karl alluded to. Has to be something simple. Dumb question but the plugs are installed…… correct

 

Yes

 

ok....good...maybe start at the air cleaner box and work to the throttle body looking for something clooging the works or taped off....just thinking out loud

 

Okay, I see. The symptoms sound like cylinder wash, where unburned fuel washes oil from the cylinder walls and reduces compression. It's basically flooding on steroids. Read this procedure:

JagRepair.com - Jaguar Repair Information Resource


The early V8 models with the Nikasil blocks were especially prone to this problem, but it can happen to any engine. In the procedure linked above, pay special attention to the note to hold the gas pedal to the floor while cranking the engine to distribute the oil. This is with the spark plugs still removed, so the engine obviously won't start yet. If you miss this step, the injectors will continue to spray fuel and quickly wash off the oil you just introduced for regaining compression. If you hold the gas pedal fully depressed, the computer shuts off fuel to clear a flooded condition.

 

Remove the cam covers and inspect the cam timing. Rotate the engine using the 24mm bolt on the crankshaft pulley in a clock direction only to see if the camshafts are still correctly timed.

 

Karl, 50 lines for you "must try and pay more attention"

 

Well, it still sounds like cylinder wash to me...

As far as the ignition system, I bet it is just fine, but can't do anything with wet plugs. Then throw in low compression thanks to all that oil being continually washed away by fresh fuel. (See the bit about holding the gas pedal to the floor to cut off the injectors.) Time will tell. I've taken the liberty of composing a follow-up message you can post when (if) we get a reported fix. Feel free to use your own words, as long as you stick to the general theme:

"Karl, you're amazing. You were right. Again. How do you do it and stay so modest? Why do I ever doubt you? I'm scum."

 

We're not worthy!

 

Hi Norri.
Drove into my garage. and pulled the intake. Jag has not moved.

 

The $64,000 Question:

Was the engine cold when you drove into the garage? You haven't really specified. If so, that is a prime condition for cylinder (or bore) wash.

If the engine was already warm, cylinder wash is not a likely culprit.


Going out on a limb here, but I'm guessing you've been cranking and cranking on the starter. No matter what the root cause may be for the failure to start, make sure you charge that poor battery before continuing. These cars are very sensitive to low prestart voltage.

 

Hi Carl.
This morning I removed plug No1 to check for spark, the plug was drowned in fuel. I dried the plug and tested .I have spark. I then removed all plugs and added a little more oil about a tablespoon to each cylinder and turned the engine over a few times keeping the accelerator pedal on the floor. I replaced the plugs and keeping the pedal on the floor. Compression is back. After trying to start a few times by slowly releasing the pedal ,I gave up. No start. I removed plug No 1. and tested for spark again. No spark. Any advice? ECU reset?

 

Okay, at some point you've had (and may still have) too much fuel in the cylinders. Good info to help troubleshoot.
Back to my previous question, still unanswered: Was the engine cold when shut off? I'm not trying to bust your butt or split hairs. But this is a YUGE detail that will help guide how to get your engine running again.


Fantastic. This is also extremely helpful. This helps rule out some new problem induced during this recent work, such as a connector not getting fully reseated. You may not have spark at the moment, but at some recent point in the process you did, so we're heading in the right direction.

Excellent! Making progress.



No, an ECU reset is not required. Was the plug wet with fuel this time? Or oil? The spark will follow the path of least resistance, and won't fire if the plug is contaminated with fuel, oil, carbon, etc.

Have you recharged the battery yet? Assuming (Danger! Danger!) it has run down from repeated start attempts, this will also weaken the spark. Even if the starter speed seems adequate, the available voltage may be getting too low for the ignition system to fire consistently. Throw in a little contamination on the plugs and that will only worsen the situation.

 

So, seems was bore wash.

A mite unlucky it didn't start with compression restored.

 

Playing Devil's advocate here. Just got to thinking about something. How do we know compression has returned? Is this determination based solely on starter cranking speed? If the battery has been run down from all these start attempts, the starter cranking speed will drop in response. So it may not be truly accurate to say compression is back, considering a depleted battery will mimic the loss of same. That's why I've stressed to make sure the battery is fully charged.

 

Back to the manual gauge compression test i think