XK8 Judder/ missfire and poor performance Error

[alamn2]

Hi

My xk8 coolant clip gave way and leaked coolant everywhere in the engine bay. i fixed the hose and topped up fluid all was fine for the day.

The following day i started the car it started but had a judder like a misfire and it just got worse with the engine light coming on with message Engine fault, Poor performance and the judder and shake was really bad.

I read the engine codes below:

P0300- random/ multiple cylinder Misfire
p0307- Cylinder 7 Misfire detected
p1316- Misfire rate exceeds emissions
p1230- Fuel Pump relay


i cleared all the codes and all but P1230 came back immediately

the performance is the same , the judder and shake and really bad smell from the exhaust.

I dont have the funds to take this to the dealers but was wondering what could be cause.. should i just change the plugs and coils to start off with or does this sound a result of the water leak causing some electrical damage?

Thank you

[J44EAG]

Did the leaked coolant perhaps flood into the spark plug wells? That wouldn`t help. Could it be that the relay could have had a coolant bath?

Mike K

[alamn2]

Did the leaked coolant perhaps flood into the spark plug wells? That wouldn`t help. Could it be that the relay could have had a coolant bath?

Mike K

lots of ifs and maybes.. i guess the best option is take out and wipe each spark plug.. when the coolant clip gave way the engine was super hot so it sprayed everywhere at an alarming rate ..

Can some one guide me on where cylinder #7 is if im standing in front of the car.. i guess thats the first inspection.
the relays are well hidden but could be suspect.

[J44EAG]

What year is the car?

Try this as a starter.

JaguarV8 cylinder layout.jpg (9.55KiB)Viewed 4761 times

Go to Google and type in "Jaguar cylinder7". Then look at images for the model, year and capacity of your car. That is where the above image came from.

Mike K

[alamn2]

It's a 1997 model

It starts ok the misfire appears to be apparent after the revs have settled down.

After clearing the codes I only get the random misfire code .

I will take each plug out inspect it and replace it if needed . And may replace all the coils too whist Iv got it apart.

[alamn2]

I just took out coil on cylinder 7.. I can barely see the tip of the spark plug it's full of liquid... is this my coolant seeping is or something else

Some quick advice please as I have it open .. what shall I do

[alamn2]

Photo attached .. any tricks to suck this liquid out

[alamn2]

What year is the car?

Try this as a starter.JaguarV8 cylinder layout.jpg

Go to Google and type in "Jaguar cylinder7". Then look at images for the model, year and capacity of your car. That is where the above image came from.

Mike K

Many thanks Mike the pic was helpful

[alamn2]

It's definitely not oil so plug gasket is ok.. I'm surprised so much of the coolant has seeped into the plug well despite the plastic cover protecting the coils

[mike020150]

Well, there's little doubt why the poor car was misfiring! I hope all will be fine once you have extracted all that water and dried out the entire area. Mike.

[alamn2]

Well, there's little doubt why the poor car was misfiring! I hope all will be fine once you have extracted all that water and dried out the entire area. Mike.

Many thanks for the help.

Iv removed all the fluid and plugs . will order a new set and put them in next week and see how she goes.

i will post an update once all have been replaced to see if all the issues have resolved.

[alamn2]

Well, there's little doubt why the poor car was misfiring! I hope all will be fine once you have extracted all that water and dried out the entire area. Mike.

Hi Mike

Just as a side note .. when removing plug number 8 .. it was rather difficult getting the spanner in so to help i unbolted the purge valve at-least thats what i think it is .. Part number LJA1515AA.. to my surprise the electrical connector was not connected it was tucked away .. considering before i purchased the car it has had extensive jag main dealer history where the invoices suggest even basic hose tie clips were replaced then why would they leave the purge valve disconnected why not just replace it and bill the customer since every annual invoice was around £3500.

I will have to test it next week now when i get the plugs in but my question is without the purge valve connected should this not throw an error code or also impact the economy / performance of the car.

[J44EAG]

The purge valve forms part of the evap system. I suppose different sales markets need different parts of the system in operation. As I understand it, the valve removes vapour from the tank system then feeds it into the induction system to dispose of the fumes.

There will probably be several other connectors tied back and being made redundant. It might nut be necessary for the plug you found to be connected...but then again it may have been left disconnected in error. Worth asking any service contacts you have whether it should be operational. You might run a diagnostic check on the EVAP system to see whether anything code wise comes up...connected or unconnected.

No 8 plug, NSR is the Devil to extract and refit. The valve usually has to be displaced to change that plug. No getting around it.

Water ingress from a scuttle area or otherwise, often finds its way between the seal on the spark plug lid and onto the rocket cover. If it does, then water will find its way into the plug wells. My old S-type had a poly sheet under the wipwr scuttle panel and lead standing water away from the rocket covers. That kept any water at bay.

Mike.