Hello jaglovers,

so has anyone found the main issue on startup then car stalls on xj6? I have a 1997 naturally aspirated 4.0. I've read many threads but have yet to find the culprit to this problem.

My problem?

Start the car, hot or cold and immediately dies. Unless I give it gas when I start the car it stay on but if i let go it dies on me. It also stalls on idle (hot or cold).

Things I have worked on/ replaced:

Belts
fuel filter
fuel pump
sparkplugs
coils
cleaned throttle body
adjusted TB cable
cleaned MAF sensor
cleaned IACV
Cleaned EGR valve
All relays have been replaced
No engine codes

Things I plan on working on in the meantime -

-replacing throttle body spring (mine sticks open when tapping gas pedal)
resulting in high RPM idle

Any ideas?

 

Transmission connector , can clean without jacking the car , left side . Tap on ( with a helper ) or replace IACV , as you throttle back it should actuate open . Are you available to use a ELM327 engine sensor reading live graph from yourself or a friend ? See example below page 2 . Have you removed and cleaned the forward 2 O2 sensors ?


https://www.jaguarforums.com/forum/x...ong%5D-184729/

 

Thank you for the quick response. I will perform all the mentioned above and will update. I will work on my jag this weekend. For now enjoy the rest of your week.

 

The existing throttle spring can be preloaded better and tighter for idle pull down response by going to the next tighter post on the butterfly shaft tower . There is a Jaguar TSB to replace the spring to a stronger one . As a foundation of what your engine needs before it's regulation by external devices focus on the correct plugs ( Champion-RC12YC ) and clean O2 sensors . The Transmission connector may not be related to your current issue but it should be on the 20 year scheduled maintenance list to prevent known engine stalling issues .

 

Well I replaced the spark plugs to the recommended (RC12YC) and car is misfiring like crazy. Gapped at 0.040. I then went to the store and picked up NGK BKR6ES Gapped around 3.8 and misfires like crazy as well. Do tall have the measurement at what it should be at?

 

Update:

I returned both set of plugs and purchased the E3 diamond spark plugs, car ran like a charm. I guess my jag has expensive tastes. Car stalling problems are no longer there, which makes me think I needed different set of plugs. Will update if stalling problem comes back up. Thank you all for the help.

 

Well 2nd update:

I replaced the throttle spring however this did not fix the high high idle as it was not strong enough to pull the draft. To fix this I hooked the old throttle spring near the throttle cable adjustment and the pin that holds the cruise control. This fixed the problem and I have attached a picture for reference. But I cleaned out the throttle body, tps, iacv, and other parts. Screwed a bolt and washer to keep spring from moving.

 

May manual says .035 for the Champion coils, but it looks like you've got it sorted anyway.

 

Thriftyshirt, this probably has nothing to do with you're problem but the throttle cable is actually in the wrong hole in that bracket. There are 2 holes in the bracket, one for manual transmissions and the other hole closest to the cam cover for automatic. If you loosen the lock nut on the adjuster you will see an M on the casting and an A on the other hole.

I have run into this problem on 2 Jaguars, a 93 XJS and a 96 XJ6, both had the cable in the wrong hole, I think from the factory.

 

I'm not OP, but that's great info. Makes me want to go check mine, ha.

 

When you say you cleaned the throttle body, you did this with the throttle body off so you could clean both sides?

 

Which position is for automatic . I never noticed a marking as I sanded it down during cleanup . The Document below was made by someone else and covers the return spring . Do you have the original factory weaker spring installed ? I'm looking into the E3.48 plugs myself .

 

Hello my friends,

I haven't messed with the bracket but when I have the chance I will look over it. I used the spring as shown on my picture posted earlier in the thread to help with the high idle issue. I had replaced the spring when I removed the throttle body and cleaned both sides, iacv, egr, and intake boot. No more high idle!! Woo!! And I replaced the coils with the QYL listed on Amazon for $72. I recommend the E3 sparkplugs but make sure to disconnect the battery beforehand. I did not have any misfiring when I tried this (did not do it when I replaced NGKs and Champions). But car still stalls on startup. So I'm not sure where to go from here.

Ideas?

Thanks.

 

Idle Air Control Valve or sticking unresponding injectors ? Below 11.5 volts on the battery the ECU gives fits so that can throw you off .

 

Hi Lady Penelope,

I disconnected the IACV and it still stalled on startup (so I do not think this is the issue). I do notice that when I start my car the voltmeter does fluctuate to low levels, enough to stall the car. I checked out the o2 sensors and they seem to be in good shape. No burnt oil on plugs or o2 sensors either. Could this be a failing alternator? I did do a test recently, had the car running and unplugged the battery. The car did struggle but was able to idle.

 

The IACV is commanded to drive open as the butterfly is closed so you have air so it would have to be connected to keep from stalling . Since you are stalling before there is time to naturally recharge the battery you are having to jump start or battery charger your battery . In a long engine run there may be a intermittent charging issue with one engine run you mentioned being ok . I made a reply to someone with some things you can do before pulling the alternator as a last resort but I haven't rang it out yet to verify a decrefincy in the Jaguar documents in relay labeling . If you put a meter on the B+ post as it is still connected during running it should read a volt or so above a fully charged battery being 12.77 volts so a B + post during charging should be above that around 13.5 to 14.5 . You can also read this at the battery itself as a safer location . A long wire test lead with clips is handy to be able to alternate method of seeing this with a meter on the seat or dash in a one person operation . I placed my battery in backward and just touched the terminals so I fried the voltage regulator and I'm a professional ( 25 dollar including shipping Ebay ) . The instrument gauge indication side of the battery/charging system I will leave alone in discussion for now .

https://www.jaguarforums.com/forum/x...-drain-187036/

 

Hello All,

I've attached a link to my video that I uploaded through Youtube. Currently temp is 78 F and humidity 88%.
I will be keeping track of when it stalls, just in case I see a correlation.

 

Is the battery charged up to the full 12.77 volts with a external meter before starting ? Have you tried starting and running the car with jumper cables still attached and once the jumper cables are removed what happens ? You can jumper it from the front engine bay . The true voltage may be too low and causing ECU to not turn fuel pump back on after initial key to on only 3-5 sec fuel rail charge / primer where the pump turns back off by design . The ECU turns it back on once it sees rotation from the crankshaft sensor .

With the following method you can hotwire the pump to stay on eliminating the ECU control :

With the fuel pump relay you're looking for the 3rd click back to on ( from the crankshaft sensor ) . Since you have the first 2 ( sometimes ) that charge / prime the fuel rail the control circuit is intact ( sometimes ) coming out of the engine ECU . You must have relay click for power to the pump . If you want to hotwire the fuel pump to stay on at all times you can put power into the relay socket that goes straight to the pump taking the control out of the picture so you can focus on a running engine's regulation . Take a blade connector with some heavy gauge wire from the forward most slot in the relay socket to the battery positive or the relay box terminal post positive . Use the clip as a switch so you don't arc the relay socket . Will be hot at all times so don't forget to remove the clip on shutdown .

 

I personally would focus on the low voltage problem for if you don't have enough voltage ( 11 volts ) the ECU will not work properly . If it gets to it you can remove the alternator and the auto parts store will spin it up in their machine to test regulator . The second link is some things you can disconnect to maybe resolve this before removing the alternator . Have them test battery also .

OEM DENSO VOLTAGE REGULATOR REPLACES 126000-1200, 8970320910, JLM-11144 IN435

If it is a true voltage problem ( and it may be intermittent in that you described movement in the voltage gauge and driveability before ) :

https://www.jaguarforums.com/forum/x...-drain-187036/

 

Well I took my car to a professional and what they are telling me is that the O2 sensors are reading a rich mixture. When they check the plugs they are advising they are lean. So the O2 sensors are not reading correctly. Could this just be that the O2 sensors are bad?

Please let me know. They still have jacklyn at the moment.