UPDATE:
Yesterday I added some transmission fluid and also installed a new Flosser relay. I don’t normally change more than one thing at a time but I have to reduce the risk of my car stalling on my long one lane driveway - blocking all in and out access and requiring a tow truck.
I took the car for 2 test drives. 1st - a 15 mile each way trip with 90 percent hwy but about 6 stops on each leg. No issues. 2nd - a 20 mile round trip on country roads with 5-6 stops. No issues.
I can’t be certain which of the 4 changes I made in the last few days may have affected the issue:
Changed plugs which looked fine.
Cleaned throttle body which was not very dirty.
Added some (1/2 -3/4 quart) transmission fluid.
New fuel relay (the one I replaced was the original and tested fine).
I can say that the transmission fluid now reads high. After the 1st test drive I left the car idling and immediately tested the level. It is at the top of the bend in the dipstick. Previously it was in the center of the hatch marks when warm. That is quite a bit higher than the hatch marks.
More test driving today.
Btw - the fluid I am using is Castrol Transmax.
Not done:
Fuel Pressure / Fuel Regulator tests
Fuel filter (Current one is less than 20k miles old)
Cleaning of transmission connector
Vacuum test for leaks
EGR clean ( was done not too long ago < 10k )
The car idles right at 700 rpm in gear at a standstill.
P.S. Check the fluid level hot…not cold…after it fills the converter, but if its good now LEAVE IT ALONE.
We were doing this years ago…
Good luck and drive on.
gtjoey1314
The transmission fluid reads high at hot now. But the warning light only came on once. I plan on cleaning the connector.
After changing the plugs and coils the car idles very smoothly at 690-700 rpm.
I drove the car fairly hard for 60-70 miles and never had an issue.
Today my wife said it drove the worst ever. Hesitation. Sounds like fuel/spark interruption. I’m going to go with another car for her to drive home and drive it home myself.
I never tested the fuel pressure as my tests did not show an issue. This is an intermittent issue so I’m inclined to think its not fuel pump/fuel filter etc. Surely it would have manifested itself when I drove it? TPS, computer or whatever. Computer was changed out once.I’ll get back when I’ve driven the car. I’m taking it off the road till I sort it out. I’ll connect my OBD system to it and see what that reveals. Fuel is perfect at 23 mpg hwy. Running Premium. No codes at all.
I also have a new spare Coolant Temperature Sensor. I’m going to test it against the installed one. I know there are several posts referencing similar issues that ended up being the CTS.
Example: CTS Issue
Bone dry. I drove it home 30 miles or so. Multiple stops at red lights. No misses or hesitation at normal speeds. The only thing I noticed is that when pulling away the “hesitation” feels a little mechanical to me. Almost cable related. After inspection this morning there is about 1/2" of movement in the pedal before the throttle starts to open. When the throttle is fully depressed there is still about 1/2" of “potential” opening of the throttle left if that makes sense. So I am inclined to thing the throttle cable needs adjustment and lubricating. That would explain the feeling when you are at a standstill on an incline and it feels hesitant when you move your foot from the brake pedal to the throttle and depressed the throttle. I’ll have to read up on the throttle linkage.
As the rear end bearings are now howling I’m taking it off her hands while I focus on getting it back in shape. 22.9 mpg. Perfect.
CTS read 195-202 on my OBD hand held reader at 70 mph on hwy.
This morning it started fine but the idle is definitely periodically rough. It went into closed loop at around 90F. I’ll hook up my computer OBD2 system this afternoon which will let me record.
Get a code reader and it will tell you what your % throttle opening is, I would bet you are at about 70% with that much slack.
Another thing to check would be the CPS wiring look for any damage to the shielding My ‘40 wold occasionally stall (usually when I was at the head of a stream of traffic at lights, now did it know?) this was the shielding shorting out and dropping the CPS signal. Replacement CPS solved thats particular problem.
Update: I adjusted the throttle linkage to eliminate the slack and it took away one of the elements of hesitation. One time on the test drive I detected a slight hesitation when pulling away that feels like fuel to me. However I am going to take the car off the road now and fix the rear end bearings which are howling before I return to this.
I’m back on this now. It appears I may have several issues. The behavior continues. Drives fine for three 20 mile trips then starts acting up:
Transmission lamp on periodically.
Hesitation/stall at slow speed pulling away, particularly bad if on incline.
Yesterday I put my code reader on the car and got a P0304 misfire code. No CEL. I tested all the coils with my HEI tester and #4 was bad - intermittent spark. I had a good old original and installed it. Fine. So much for the coils I bought in MAY! One thing I noticed was a powder on the end of the coil contact that engages with the plugs. Cleaned them. Tested all others.
Idled good. Ran car 5 miles. Stopped to turn around on incline. Car stalled out under load when trying to pull away. Had to apply high revs. On way home the transmission light came on , which has been intermittent throughout. Prior to the test drive I thoroughly cleaned the electrical connector on the transmission.
Later today I have a new CTS sensor coming.
After I got home I put code reader on and got the 2 infamous codes - P13B0 & B30F4 which one has ever been able to shed light on. However I did find this link fwiw that suggests a CPS issue. P13B0 Code Link CPS Issue?
At this point I’m going to start looking at vacuum & electrical connections. I have not performed a fuel pressure test yet but am inclined to think its not that.
One other thing - I looked at the O2 Sensor voltage patterns and they are not consistent. O2 sensors?
PS I’m not alone. I can find any number of posts with similar behavior patterns on the X300. Never definitive conclusions.
At this point I do not trust the coils. I’m looking for OE used ones. The spark on the HEI tester using an original OE coil was much stronger. The aftermarket coils also did not have that minor gap before being bolted down reflecting some pressure on the internal spring.
SNG Barratt at least puts a year warranty on the aftermarkets they sell. That’s one option.
You can also try Beck-Arnley and roll the dice.
I’ve always been interested in the quality of the Standard brand on Rock Auto.
The last option I would spend any real money on are old, used, mystery coils. That’s just my two cents.
I googled the coil numbers and purchased 16 from China to replace the ones in my ‘99 XJR (contingency incase some failed) haven’t had to replace any in the last 4 years, and they were reasonably priced.
All - I’m not going to gamble on 30 year old coils - especially when they have hairline cracks in them. I have acquired 5 new Lucas Coils made in GB and I have a few of my original coils which test good.
I did have decent time on Beck and Arnleys. Short time on QYL and the last go around I got one bad coil in 2 months. So Chinese is a crap shoot.
There is no real indication as to whether the SNG aftermarket are any better at $30+ each although they are likely the best available as SNG are such a good resource. They do have the greenish color at the end which at least is different to the solid black ones - QYL and the last ones I got. 12 months warranty doesn’t mean much to me. They all have that although replacement from SNG would be infinitely easier.
I’ve sourced new Lucas coils for $50 ea. I believe that is the best way to go. These are not the fake ones off Ebay.
I also understand that spikes from coils can cause ECU “interruptions” that will cause the transmission lamp to come on, so good coils may solve my issue there. We’ll have to see. From a very reliable Jaguar mechanic who worked on these cars for years. I also understand the ECU has some form of built in protection to protect itself from this.
I’m waiting on connectors and I’m going to peel back the harness to make sure all the wires are good to the coils. If anyone needs these connectors they are the same ones that are used on some Fords and Ballenger Motor Sports sells kits or pigtails for less than $10 ea. Great connector source. Elsewhere $30 each. I’ll post images when I receive the connectors and verify fitment.
First of all, if you still have the QYLs, I would love to see some pics of the coil, without the boot, and the spring and rod it used.
Secondly, the Lucas coils do not have a good reputation. As you can compare to your Chinese cheapies, they use black coating at the top, and a silver bolt hole. The better coils, from Diamond, seem to use the yellowy epoxy at the top with a rectangular protrusion for some reason, and they tend to have brass colored bolt holes.
Please keep the forum informed on these coils. Always good to know, for better or worse.
With love, GTJOEY1314
