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Have you ever had this Car running properly, or did these problems only occur after you had the Fuel Tank Cleaned
Never ran properly, ever since I bought it. Was initially missing, wouldn't always start, wouldn't change out of first gear, brakes needed to be rebuild, as did the suspension, etc.. A lot of muppets had no doubt fiddled with it over its 30 plus year life and certainly not for the better. It is now all sorted, save for this last remaining annoying issue. I say "last" with my fingers crossed.
Many years ago I had a very fast Range Rover, and afetr a service it would not pull over about 80 mph. It seemed Ok for a bit but then would not pull at high revs and high loads. It turned out to be a duff new Bosch fuel filter than was self-clogging because the element inside was malformed. I would fit a new filter for sure.
Have you checked the connector into the Marelli ECU in the footwell?
Still I say change the HT leads for new ones.
Still I do not completely believe that your verifying of the amplifiers proved they are not the trouble. My money on the amplifiers and their associate wiring as the symptoms are what you would expect from an electronic component breaking down as it heats up.
Fuel filter - Crossed my mind too. Maybe even that is was placed backwards, or something... Its got to be something simple-ish...
Also, that after changing so many parts new,,, thinking that new means working perfectly. I have placed NEW things that were broke out the box...
If you can get a Fuel Pressure Reading at the Fuel Rail, that might go a very long way in helping to solve the problem, as then at least we can eliminate that for the time being
I've also thought of a 'Worst Case Scenario' but would like a 2nd opinion from someone who knows
Could there be a Stuck Lifter holding a Valve open?
More thoughts, and not all related to when it warms up.
Engine earth strap fiasco at teh LH engine mount area. Run a dedicated strap engine to chasis. That double thing was n good from new.
Inlet manifold nuts (24), are the tight, The V12 is known for that "cardboard" spec gasket to settle and the manifold gets loose. NOT stupid tight, just good firm.
The AAV I am assuming is closing 100%. That would reek havoc if its not, more so at idle, but also at WOT, especially when engine temp is getting towards normal.
The is a very dim bell ringing about FPR changes at either build date (1989ish), or engine number????. I will look at my huge Bosh books later and come back with what I find.
UP TO 9/89 0 280 160 214 (2.5 bar)
UP TO 9/89 0 280 160 234 (3.0 bar)
I forget the spec difference, and if I remember, or find anymore scribblings in the shed, I will update here.
FROM 9/89 0 280 160 508. NO BAR READING GIVEN, and I cannot a spec on a quick Google.
My contact at Bosh has retired, like me, whoopee, and the Gem I spoke to had no idea.
Since you are 1991, the ..... 508 is the one correct for your car.
The AAV is easily serviced, about 6 beers for the novice. I have them out, services, reglued and drying within 30 minutes, since i got better the more I did.
The moment that Grant mentioned it, All The Lights Came On!
As I am now more than ever convinced that this could be another stroke of Genius by Grant!
Being that the AAV (automatic air valve) could well be symptomatic of your Engine 'Bogging Down'
Since one of these can cost more than the Price of a good Secondhand Car, then it could well be worth trying Grant's fix to see if this is the Miracle Cure we have been looking for!
Are these connections correct (Strategy Selection Link)?
Also,
- pulled out the O2 sensors to create an exhaust leak. But problem still there. Hence I can only conclude it is not a blocked exhaust.
- checked and tightened all 24 inlet manifold nuts
Will check AAV next, as suggested, but can’t imagine that to cause it to miss as it approaches 3000rpm.
Never ran properly, ever since I bought it. Was initially missing, wouldn't always start, wouldn't change out of first gear, brakes needed to be rebuild, as did the suspension, etc.. A lot of muppets had no doubt fiddled with it over its 30 plus year life and certainly not for the better. It is now all sorted, save for this last remaining annoying issue. I say "last" with my fingers crossed.
The question was related to the issue you are having and the subject of this thread. Has the car ALWAYS gotten funky around 3K rpms since you've had it...?
The reason it's being asked is because you've done significant work to items/systems that would cause the 3k issue. Plug leads, sheilded wire, fuel system etc...
And removing and running with open O2 sensor holes open may or may not rule out the way that (does this car have CATs an obstruction in the honeycomb of the cats up near the engine in the downpipe. Looks like this:
Well, I thought I nailed it this morning after having checked the operation of the AAV as per Grant’s instructions, cleaned engine earth strap connections, installed the strategy link for higher octane 98 fuel I’m running and removed and cleaned the CPS and FPS, which looked a right mess.
Took it out on my usual test run, out the driveway and up a steep incline in first. Put the foot down and it spun the rear wheels as it accelerated spinning out to 4500rpm before dropping into second. Feeling somewhat euphoric I continued the drive for a few more kms as it warmed up to operating temp.
Gave it another squirt in first and I felt somewhat deflated as the familiar splutter and missing occurred as it approach 3000rpm. Ahhhhhhh!
A quick check back home; disconnected the A-bank Amp and injectors to run and rev out only to find that it spluttered and missed. Did the same with just running on A-bank and similarly the miss was on that side too.
If it ran ok once then it can do it again, only for longer next time
Check the Gap on the Crank Sensor and make the Gap a bit Smaller, do it by eye if you have to and if possible give the Toothed Wheel a good Squirt of Carb Cleaner and Clean the Crank Sensor again
After your Test drive you may agree that the Front Crank Sensor could well be the Problem
But next time let the Engine Warm up before you go and take her out on the road (at least just this once!)
We want to see your Car Fixed, even more than you do if that's possible!
Check the Gap on the Crank Sensor and make the Gap a bit Smaller, do it by eye if you have to and if possible give the Toothed Wheel a good Squirt of Carb Cleaner and Clean the Crank Sensor
Hi Alex,
you say to check the gap on the CPS, but I’m not sure how that can be adjusted as it is a fixed fitting. No adjustment, it certainly wouldn’t be able to sit in any further as it is, as the sensor outer edge is virtually touching the edge of the harmonic balance.
On my Car I had to either put a Shim in or File the holes in the Bracket a fraction longer (can't remember which one I did) but if the Gap is too wide, then she won't run properly, if at all
B Bank is all that Bosch recognise.
UP TO 9/89 0 280 160 214 (2.5 bar)
UP TO 9/89 0 280 160 234 (3.0 bar)
I forget the spec difference, and if I remember, or find anymore scribblings in the shed, I will update here.
FROM 9/89 0 280 160 508. NO BAR READING GIVEN, and I cannot a spec on a quick Google.
Since you are 1991, the ..... 508 is the one correct for your car.
Interesting Grant,
The FPR on my B-bank is a 0 280 160 229. None of what you listed. With respect to the new new FPR that I purchased to try and made things worse, that didn’t have any markings on it at all. I assume it came from some obscure country, but listed as a EAC4864, per the parts manual.
Not sure why it ran considerably worse, almost to the point of stalling, but that being the case I may sill have an issue with that old FPR. Though it worked a lot better than the new one I tried.
Anyway, I think a fuel pressure test is next as most everything else has been exhausted.
I'm sure you dread all the well-meaning but often naive suggestions that people like me are making to try and resolve your problem! The truth is that many of us are so interested in the process and eventual outcome because we all think "There, but for the grace of God, goes my own car". So many of the symptoms and potential updates / fixes are common to our own V12 running problems that it makes for an addictive thread!
As I keep re-reading your feedback and analysis, it feels that the problem is all about a component (or combination of components) malfunctioning. And with your recent revelation that it actually seemed to run ok on initial startup, the factor now seems to be about one (or both) of the criteria of Time or Temperature.
At the real risk of potentially sounding like what I know what I'm talking about, my analytic head says that I would write down each of the potential fail components and logically test / assess the against the 2 criteria. Some seem to fall naturally into one category, whereas some could be both. As an eg
ECU, Amplifier breakdown - Temperature
Fuel Pressure - Time?
Fuel Pump - Temp
CPS inefficiency / breakdown- Temperature?
FPR deterioration - Time / Temp?
Fuel Filter efficiency - Time
Exhaust blockage - Neither / Temperature
Etc, etc.
Apols, I did say that you probably wouldn't want to hear any more suggestions!
I can find NO listing for ANY car for that 229 FPR, in all my books. Google, gotta luv them, has NO info either.
Bosch Gem again, nope on that number also, BUT, at least he is going to do a system search and email me next week??? It maybe a None Bosch Aust Part Number.
ALSO
NO other car runs that 508 FPR.
Many others run the earlier FPR numbers.
Not convinced the FPR to be going hissy with temp, would be a first for me.
The B Bank CTS. 0 280 130 026, is always a suspect on the V12, and the White topped units especially so. The replacement are/were Blue, and same as GMH, Ford, and most other Infected cars.
The A Bank Sensor, NO idea.
The ....026 was $22 last time I needed one, and it got the point I replaced that sucker at the same time I did all the other "catch up" stuff under the bonnet of a new arrival.
BUT my experience with that CTS is mostly a dead engine, not a splutterer.
The simple test is to unplug that sensor, bridge the terminals in the plug, thus fooling the ECU to read operating temp. If that sorts it, replace said sensor.
Might be worth a clip in both of them, and see what raises its ugly head?
You mentioned testing that sensor at 80C. Mmm, that is Pre stat opening, so engine still warming up. ECU would still be supplying a longer Injector Pulse I would think. Most specs are generally Ohms @ 100C.
02-13-2022, 03:30 PM
