Hey everyone. Just registered here to help fixing my friends 2003 STR 4.2 Supercharged (LH Drive). He bought a couple of months ago and things are not going well at all.

Short story: We are in Brazil, so S-types are very rare here, and a STR is jus what we call "A white blu eyed fly" (Maybe Unicorn is a better translation eheheh). Car has 80.000km (50.000mls) that seems original. But there is a huge catch...He bought in auction. Yep! If you don't like to read all, just see the video on the bottom.

Long Story for background:
Seemed to be quarter rear ended or maybe the old owner tryied to drift it. Who knows... but was minor damaged on the rear left and he fixed. The damage didn't do nothing to the axle. Was really just the tailight, bumper, etc. The audio module was missing so a guy did a "bypass" of some sort for him.

The problem? Well it never ran right. Always rough and actually when cold you had to stat it givin about half gas pedal. Than it started (with rich mixture you could smell a block away), then if it warms up by holding it on about 3k RPM, when warm it "kinda worked". Was able to idle with only some weird minor misfires appearing to be in all cylinders.

He runs a Tyre Shop. The ones that has lots of mechanics and they kinda do everything there. But hey... we are in Brazil... no, we don't have monkeys and carnival like the stereotype, but the average good car here is a Corolla. So... nobody knows how to deal with Jags. But anyway they cleaned the injectors, changed spark plugs (where all mixed brands and types), diagnosed it with a good scanner, and it where trowing him some coil errors, but kinda random. Usualy like 3, 4, 6 at same time, but sometimes some cylinders, some time others, really funky. Also the Lambdas (the ones with the gray wire. Forgot how you call them. downstream I think) on both banks.

He proceeded to change ALL coils with original (or at least we think) ones from Delphi, and bought on the Jaguar Dealer both lambdas as HE KNOWS that on those Jags there is no tollerance for aftermarket stuff.

Well to be quicker, it ranned even poorer. Actually know you can even drive it anymore. It doesnt Idle.

He sent it to a couple of mechanics including a "local ECU Guru" that just condemned his ECU.

Again, we are in a very small city. Yes there is talented guys everywhere, but I'm always skeptical. And my friend ended up throwing me the car as I have a micro shop/atelier specialized on installing standalone ECUS.

I really think it could be some stupid ground or something. So I'm trying to save her.

VIDEOS of the car running badly:

When kinda warm, without giving gas, starts sounding fine and imediatly shuts down
https://drive.google.com/file/d/1QO7...ew?usp=sharing


Warm engine, holding the gas close to 50% to keep it on the 3k RPM range (Is burbling a lot. Obviously due to rich mixture).
https://drive.google.com/file/d/1QzS...ew?usp=sharing

 

NOW FOR WHAT I'VE DONE (promise to keep it short as possible)

- Used damn cheap ELM327 to at least give it a look. Same errors as my friend's awesome scanner: Both lambdas "open circuit" (and no reading) and 8 coils (probably when it cuts them to protect itself it throws the error)
- Tried to start. Cold start has no signal. It fires only with gas pedal at about 50%. Revs to 3k and immediatly throws orange "Performance restriction". Very rich mixture (I mean... it makes you cry on a large garage). Warm starts seeming normal and cuts. Giving gas, keeps runing but veeery rich.
- Scanning when on: Everything seems normal. Reads all correctly. Except the both Lambdas (that where already changed for new ones).
- Tested various connectors to check for oxide and looseness. Everything seems to work. MAF looking good and appears to be reading fine. Stock DENSO unit.
- Tooked the Blow by line out of the head and pluged it with my finger. Tried to start it. Same results. Hose seems fine. No oil on the separator (UFO looking thing). Then I discovered that STR doesnt really has a PCV. Just the separator (I guess because it's supercharged)


NOW something happened:

- Looked at the ECU Harness and noticed the plastic humidity protection to be broken. And there was some low quality insulation on the first 30cm of the harness. I opened the insulating corrugate and found this:



- Looks to me that those splices are oxidated. And yes, I already know they are stok splices and some are for the damn O2.
- Opened the ECU to look for umidity or oxide signs. Nothing! looks perfect.
- ECU Main conector looks perfect
- Did ground continuity tests: All good. Low resistance with car body (no more than 1.5ohms on a couple and mainly 0.4ohms on majority)
- Checked for +12V. It's good.
- Proceeded to test continuity on the O2 wires. All ok.
- Decided to test voltage on O2 wires. Noticed one received +2.4v on the heating and the other 9.2v. Weird....
- Checked all O2 relays and fuses. Had oxide on them, but nothing extraordinary. Cleaned all and put it back. No effect.
- Measured for any frequency on the O2 heating. Nothing... suposedly it's PWM heated so... should be receiving something.
- Checked the main sensors ground (blacks and black/green on the splices). All good.



NOW... I bought a good USB PC scanner and also a KESS (Mainly because I wanted to... but will check the ECU for remapped parameters and try flashing a new stock file also. I have experience on the area, mainly older BMW's. Not with Jags tho.).

ANd also.. I KNOW that those lambda errors sholudn't mess so much with the car. Actually when cold the O2 should be ignored until heated. That's what I dont understand in this car... it looks that the ECU is really crazy. But it consistently gives me those same errors. It's like there is a wiring problem.

Lastly... Yeah I didn't opened those oxidated splices yet, but as it should be only the shileding there... shoudn't be a problem. BUT I will do anyway.



What's your toughts?
Should I quit the cause? Send it back and never look back? Maybe run to mommy? Or just kill it with fire? eheehhe

 

Have you checked fuel pressure? I don't think your car will have a test fitting at the injector rail. But if so equipped, connect a mechanical gauge there and compare to the value shown on your scanner. If no test port, you'll have to rely on the scanner alone.

I agree with your theory on the O2 sensors. Even if failed (broken wire, for example), the computer doesn't rely on that data until the sensors warm up. The engine should start okay, even if it runs poorly once going into closed loop control.

 

Leave the PCM as it is!!

Already it is likely the previous changes have made the problems worse.

Worry that some parts are wrong - check, check, check them.

Idle & misfires ... suspect air leak(s) - if all parts are good.

 

What temperature are you getting when you start the car? I had a bad temp sensor and it showed negative temperatures, car would never run right.... Until I replaced it. Same exact issue, but you should see a crazy number with the scanner...

 

Good idea.

 

You probably checked the battery, but if not, it should have 12.5 volts or close to it. When my old battery was on it's last legs the computer was like Hal in 2001, totally wacko.

 

12.5V is quite low. 12.8 is a better target.

 

Hello! Thanks for replying. I will try to do so. I actually relied on the electronic one But totally agree with testing it to be shure

 

Yeah it was my best guess for starters, but I just coudn't debunk any air leaks. I even tryied closing the UFO separator with my fingers and it didn't changed anything.

Any other common failure point?

 

Yeah I noiced every Jag owner just tells me "did you check the battery". Must be some real issue ehehehe. I Covered it by always lefting my charged ON on my attempts so it keeps on 13V+

That being said... I cant say it's a good battery brand, even if it is new. Does it require any special (AGR?) type of battery? Would a bad battery REALLY mess that much up?

 

Excellent post! I did it because as you, I've already had issues with IAT. Drove me crazy as it was intermittent.

 

So, did a couple of videos of the last trial. All short ones. Hope you guys could see something I didn't:

Bear in mind it is so rich that we were almost crying, and the car only runs if you keep it about 2.500+ with near half gas pressed:


Showing Lambdas with strange values

More on the Lambdas

Difficulty to start, and also the bad "crackling" sounds on the exhaust (due to being super rich) and the other lambda finally got heated to show values (and one is dead)

Cranking with the pedal on idle position, looking at basic scanner data - and a bang in the end. It loves to bang...



Still.... there is no way the lambdas are doing all this mess. I'm missing something for shure!

2 things intrigue me:
- Scanner gives me a almost identical VIN code to the car. 1 number is different only. Should it be identical or is it normal to have differences?
- Of all data that scanner gives me, there is one I find it bizzare: Calculated load is always on 39,6% with engine off. When we turn it on, it stays there until we give it gas. Than it would go to 49, 60+- (as giving to much gas just shuts the whole engine off). Butwhen it's off, it's again on 39,6% static. Shouldn't it be ZERO?

 

Exhaust noise may be wrecked cat. conv.

 

Could be, but wouldn't make the car just dont work at all and be thaaat rich. I mean this thing is just swiming in gas.

 

Just a thought: Have you checked fuel pressure at the rail with a mechanical gauge?