Also posted in General Help, but I'm casting a wide net:

My mechanic just finished the engine swap on my 1999 XJR; :new engine was from a 2000 XJR. New engine not starting, but seems to be getting lots of full from the injectors. I think the new engine sat for about 8-9 months before I found it. I have been over to check it out, but I know he has used plugs, engine harness, and coils from both the new engine and the old.

I can think of 2 possibilities: either the injectors are stuck open after being idle for so long or the cpu needs to be re-flashed. Any other ideas, suggestions, know-how anyone can offer before I go through the trouble of changing injectors?

I appreciate the help

Tex

 

Here is a thread with some info that might help.
https://www.jaguarforums.com/forum/s...uick+reference

The 2000 engine is a AJ27 one, and your old engine was a AJ26.

Not sure if you can reuse the injectors etc.

Have you reused AJ26 camshaft wheel (AJ26 has 1 vane, AJ27 has 4) and flywheel?

Andre.

 

As a quick check, look to see if you have the same number of cam sensors. The early engine had only one sensor on the LH head, the later had a sensor on each cam. They do not interchange.

 

Thanks for the info. Its always nice to have your monumental error pointed out on a public forum. I'm an optimist, so I want to explore what, if anything, I can do to salvage the swap. The new engine has 40k miles on it and is in great shape, and I was able to pick it up for substantially less than expected. It would be a damn shame to have to take it out and find another one.

I think my error was that I assumed that the AJ27 changes related mainly to the VVT, but that the changes to the SC engine were not such that it would be imcompatible with an AJ26 car. But, I now understand the changes were a bit more extensive than I thought, particularly with regard to starting. Below are what I think the relevant changes between the AJ26 and the AJ27 (but I defer to those with greater knowledge and skill and appreciate any corrections or additional info that may help):

1. VVT system (n/a cars)
2. Air assisted fuel injection (n/a only or also in the SC engine?)
3. Electonic throttle and new throttle body, also changes cruise control hardware as a result.
4. 4 tooth cam position on both banks and sensors on both banks
5. New driveplate and crank sensor
6. new ECM and modified ems/diagnostics, new engine harness
7. higher capacity oil pump

While there may be other changes, I think these are the main ones affecting interchangeability. For the SC engines, VVT is not an issue and I do not know if the air assist fuel injection applies. It seems that the main issues with interchangeability are the two Avos and Ken pointed out, that being the dual cam position sensor and updated sensor rings, as well as the driveplate/crank sensor changes. If my car is looking for 1 pulse from 1 cam sensor and 2 pulses from the crank sensor, but is receiving 4 pulses from the cam position sensors and 1 pulse from the crank sensor, then the ECM would process the ignition signals incorrectly and fire the cylinders incorrectly. The new ECM changes related to throttle control would exacerbate the problem.

Possible solutions. Any opinions/prior experience would be greatly appreciated. First, is it possible to just swap the ECM and engine harness, put on a AJ27 throttle body, and solve the communitcations problems. On the other hand, is it possible to swap the camshaft on the B bank, disconnect signal from the A bank, swap the driveplate, and use the AJ 26 harness, thus getting AJ26 signals from the new engine? Anything I am missing or misunderstanding?

As always, I appreciate the help!!

 

You need the 2000 spec engine loom and ecu. Check that they have the same pin arrangement going into the bcm. Get a JTIS disc, ebay is a source this this. Otherwise you'll go nowhere fast and end up with a frankenloom. Also a code reader.
Injectors should be fine. Timing plate, sensors and anti knock sensors should all report to the ecu. This is to ensure you use your later engine. Why try and make a 27 into a 26? it wont work.

Just a thought once running, you may need the later cats, as they have 4x O2 sensors, against the earlier x2?
________
Yamaha XS1100

 

Thanks Sean. I have the JTIS cd and a code reader. When you say "2000 spec loom" I assume you are referring to what I call the engine harness. If so, I have that as well. What I don't have is the ECM, although I think I can get it from the same car as the engine came from. At this point, I don't really care if it is a 26 or 27 engine. The reason I consider swapping components is because they are sitting there on the old engine and, thus, are readily available. But, I also cringe at the thought of replacing a camshaft or two, or the heads, or the driveplate, so if the ECM is available and is an easy swap, then I prefer that route. What I absolutely can't do is waste more time trying to fix my mistake, one way or the other, only to learn later that it is impossible to interchange these engines.

I understand about the BCM and the poin arrangement. I also recall that there may be three different ECM possibilities, but can't recall whether they must match up to the car or the engine. I may be way off, but if someone has a quick answer to that question before I go search it out, I'd love to hear it.

 

1 and 2 are only for the NA cars. Small note, the NA cars already got the AJ27 engine in 99, the SC cars in 00.

Swapping the ECU would be the toughest one, and no guarantees you will ever get it to work, I would totally forget that route.

You can use the AJ26 inlet camshafts (exhausts are the same iirc), or change only the camshaft wheel, then you must change the driveplate. That should do it.

 

Success!! . . . sort of. I finally had time to swap the drive plate and the intake cams and the car starts now! Running pretty rough, though. Not sure if this is a matter of slight error in setting the timing, bad gas sitting in the tank for several months, etc., etc. I did not change over the injectors and intake manifolds, cam position sensor, knock sensors. Any word on whether any of those are "must do" on the supercharged engine? I'm still taking suggestions and input from anyone who has them and thankful beyond belief for all the help so far.

On a side note, anyone want to venture a guess as to how long it takes to fish a bolt and several washers out of the front cover AFTER the cams and primary tensioners have been changed and the front of the engine put back together?

 

I'm happy to report that the engine swap is now completely completed. Thanks to everyone for all the help and suggestions, both in this thread and elsewhere, especially Avos, JTO, Brutal, and everyone else that took the time to lend advice or support. I could never have accomplished the swap without this forum, as well as a few posts by Avos and JTO from other sources.

The roughness I reported a few days ago has been resolved and the engine runs smooth as can be, so much smoother than the engine it replaced. I re-set the timing and took it for a 20 minute drive, which seemed to burn off most of the moisture in the engine. I feared a blown head gasket, but it appears not to be the case. Compression and leakdown are fine and no exhaust smoke. I have had it up and running for 3 days and no issues from the engine yet, so I am growing more confident that its good to go. I have ABS/traction/stability fail lights on, but I suspect that is a battery charge issue or sensor cleaning issue. Battery needed recharging to get the car started and may need replacement. I have seen that issue before.

If anyone wants to know the details of how to swap an AJ26 for an AJ27, I am happy to let you benefit from my mistakes and education. I also seem to have an AJ26 unit on my hands that I am willing to part with for whatever it is worth. Otherwise I will start parting it out if I can.

Anyway, thanks a ton to all those that helped out. Now, on to the suspension . . .

 

Sorry for the difficulties but if you had wanted a Honda, you could have bought a Honda. Now you have a fully functional (almost), classic, high performance sports car perhaps you would share the secrets of you success.

Seriously, with your extensive, current, hands-on experience I am sure a great deal of folks would appreciate a summation of the issues involved in an engine swap. Even if there are several old/new pairings each with their own set of issues a list of yours would be beneficial.

You might get a permanent place on the XK8/R Sticky FAQ list for your efforts.

 

So am I to understand that the aj26 has ONE cam position sensor? on one of the heads? I looked at my 98 XK8 and I have a cam position sensor on each head.

 

JTIS says that the '98 AJ26 engine has one cam position sensor on the 'B' (left) bank at the rear of the intake cam. The ring gear has one tooth.

The '99 AJ27 engine is listed as having a 4 tooth ring gear on both intake cams, except the XKR that retains the single tooth, single side arrangement.

Yes, I know, the XKR did not come out until '00. The Brits use a funny calendar when it comes to MY.

 

i have an 01 xjr witch is Aj27 how and what kinda engine i need