I'm now thinking of cleaning the cam sensor, as a mechanic suggested. Looking at the engine, it seems I'll have to remove the VANOS solenoid first, what else will I need to get/do?
Also, I disconnected the MAF as discussed, and oddly there was no engine light. Any idea why? It does go on when I start the car, so the bulb works.
1999 BMW Z3 2.8 Roadster - show project
1970 VW 411L Auto - show/restoration project (sold)
1982 BMW 518i E12/8 - stolen
1987 Mazda 323 1.5 SL - daily driver, backup show car
I thought that a disconnected MAF would trigger the check engine light...
Anyway, I drove a bit without the MAF, reconnected it, and disconnected it again (some of it after posting that). It does seem to run smoother without the MAF, as long as I don't give it too much throttle (then it bogs down, and then I need to rev it to at least 3.5k so it can clear up). It's still rather weak though.
EDIT: Oh, and the throttle response and lack of willingness to rev is unchanged.
Last edited by JKuhn; 11-27-2017 at 04:36 PM.
1999 BMW Z3 2.8 Roadster - show project
1970 VW 411L Auto - show/restoration project (sold)
1982 BMW 518i E12/8 - stolen
1987 Mazda 323 1.5 SL - daily driver, backup show car
Mine sits at 96-97 while driving.
1999 BMW Z3 2.8 Roadster - show project
1970 VW 411L Auto - show/restoration project (sold)
1982 BMW 518i E12/8 - stolen
1987 Mazda 323 1.5 SL - daily driver, backup show car
I already came to the conclusion that it's probably not the MAF.
The plugs are new, but I don't know the conditions of the coils and injectors.
Last edited by JKuhn; 12-11-2017 at 02:07 PM.
1999 BMW Z3 2.8 Roadster - show project
1970 VW 411L Auto - show/restoration project (sold)
1982 BMW 518i E12/8 - stolen
1987 Mazda 323 1.5 SL - daily driver, backup show car
I'm wondering now. I started considering that it might be a failing coil (looking again I see it was mentioned), what are the odds? I also noticed today after doing a long distance trip that the car backfired slightly on acceleration, and not only with the throttle closed.
Can a bad coil cause driveability issues at low to medium RPM, while working well at high RPM? It doesn't make sense to me, but I'm trying to look at everything. If the coils are suspect, a local mechanic might be able to test them for me before he closes later this week.
1999 BMW Z3 2.8 Roadster - show project
1970 VW 411L Auto - show/restoration project (sold)
1982 BMW 518i E12/8 - stolen
1987 Mazda 323 1.5 SL - daily driver, backup show car
Reading DTC codes or checking engine roughness in INPA might give you some idea which cylinders have issues, so by swapping coils around you might rule out the failing one. Don't have experience with failing coils, but I know that some people were mentioning issues with them on z3 in this forum, so can't rule that out.
Maybe injectors are failing? Work properly on high pressure (on higher RPM) only? Again swapping them around and comparing before/after DTC codes/engine roughness could help locate issue IMHO...
Last edited by deni2s; 12-13-2017 at 06:15 PM.
Usually when coils are bad enough to cause a misfire they also throw a code for their cylinder. You can then swap coils from cylinder to cylinder and if the code follows where you moved the coil to, the coil is the problem.
Without a CEL or further diagnostics (INPA reading live data to see whats going wrong), you are flying blind...
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There aren't any such codes (unless they started showing after the latest test).
I did however notice that the Z3 is aparrantly supposed to have two engine lights, while on mine only the EML seems to work. So I'll have to find the reason.
1999 BMW Z3 2.8 Roadster - show project
1970 VW 411L Auto - show/restoration project (sold)
1982 BMW 518i E12/8 - stolen
1987 Mazda 323 1.5 SL - daily driver, backup show car
When you put the key in at start, the check engine light doesnt turn on?
How are you sure you dont have codes and not that the previous owner removed check engine light bulb? Has happened to me before
The codes have been checked a couple times. Once when I won a diagnostics test, once when I went for a second test (I had my doubts about the first one), and then again when the mechanic I use did some work on the car.
1999 BMW Z3 2.8 Roadster - show project
1970 VW 411L Auto - show/restoration project (sold)
1982 BMW 518i E12/8 - stolen
1987 Mazda 323 1.5 SL - daily driver, backup show car
So you have no codes not even shadow codes? Strange...if its running as badly as you say I would expect it to set at least something... Have you done a simple compression test?
I have had vehicles in the past where the only sign of a blown head gasket was poor performance and loss of compression between two pots. That was in the days before obd.
I am not sure of the water jacket config on the M52 but it may be possible that the gasket can be blown between cylinders or the head can be cracked without it absolutely being into the water jacket and then there can be no coolant loss but poor or erratic performance.
But won't bad compression (rings, valves, head or gasket) cause bad performance throughout the rev range? That's why I don't think it's something like that.
It did throw codes, but most of them cleared:
DTC 41: Camshaft signal, inlet (did not clear)
DTC 154: Unknown (cleared)
DTC D7: Oxygen sensor behind cat bank 1 no signal (came back)
DTC D8: Same as above, bank 2
DTC CA: Fuel trim bank 1 control limit (cleared)
DTC 67: VANOS inlet cam, end position not reached (if I'm not mistaken this one also cleared)
DTC CB: Fuel trim bank 2 control limit (cleared)
DTC 98: Oxygen sensor voltage behind cat bank 1 (I think it cleared)
So obviously the downstream O2 sensors are bad, but I'm told it won't cause these issues. Also keep in mind the exhaust has been decatted by a previous owner. And then there's the intake cam code (P0340), which didn't clear. Now that makes me think it might have something to do with the intake cam, but I'm not sure what to make of it. From what I hear a bad cam sensor will result in either a hard start or a no-start situation. But the car almost always starts immediately (relatively speaking, it takes long to me but I'm used to carbs that start with a single pulse of the starter). If it's a problem on the circuit, won't that also cause the car to not start? Or at least unpredicatble performance as the wiring moves around? But, if it's the base cam timing as people have suggested, then it should be more consistent (as it is the car will sometimes pull very well on the bottom end for a couple km after starting it again (can be after standing a couple hours, or after refilling the petrol tank)).
I also spoke to the mechanic that I'm using at the moment. He feels checking the base cam timing is unneeded as bad timing should bend the valves (as I understand this is a non-interference engine so that won't happen). He can also clean the cam sensor, and he suggested that at one point.
Anyway, I'll update the OP with the latest info.
1999 BMW Z3 2.8 Roadster - show project
1970 VW 411L Auto - show/restoration project (sold)
1982 BMW 518i E12/8 - stolen
1987 Mazda 323 1.5 SL - daily driver, backup show car
Don't rule out a bad Maf, they don't always set codes showing they are duff, however they will cause other sensors to misinterpret any wrong data the Maf may be sending or not sending to the ecu leading you off on a wild goose chase for faulty sensors. If the car ran ok with the Maf disconnected it would have been using a default setting to achieve best running. It wouldn't be perfect but better than a duff maf connected. Car bogging down at higher revs is another sign of a bad Maf.
Mafs are not cheap, always use Bosch or Seimens oem makes do not buy cheap pattern Mafs they are of dubious quality and rarely work or last long. You could try a used oem Maf from a breaker, if it is your Maf then putting in a working one will instantly fix your running problems. It did when my Maf gave up. Considering the age of our cars its not surprising sensors start failing.
.... you have a camshaft position sensor code and you're NOT (?!?) changing the camshaft position sensor first? Cleaning it?????
All going by how the car is supposed to behave when it's bad?
-Abel
- E36 328is ~210-220whp: Lots of Mods.
- 2000 Z3: Many Mods.
- 2003 VW Jetta TDI Manual 47-50mpg
- 1999 S52 Estoril M Coupe
- 2014 328d Wagon, self-tuned, 270hp/430ft-lbs
- 2019 M2 Competition, self-tuned, 504whp
- 2016 Mini Cooper S
So I should rather just outright replace the intake cam sensor?
As I said, everybody told me a bad sensor should at the very least cause hard starting.
colb: But like I said, it's running bad at low to medium RPM, not high.
1999 BMW Z3 2.8 Roadster - show project
1970 VW 411L Auto - show/restoration project (sold)
1982 BMW 518i E12/8 - stolen
1987 Mazda 323 1.5 SL - daily driver, backup show car
Crank sensors prevent starting
Cam sensors can cause your symptoms
What a fun diagnostic adventure this has been
My occupational hypnotherapist says I need to quit following this thread
I'll see when I can do it then.
Just keep in mind that 1) I'm used to carbs, not all these computers, and 2) I'm hesitant to just replace a presumably expensive sensor if one bad sensor can cause others to show as faulty. So essentially I don't fully trust the diagnostic printouts.
1999 BMW Z3 2.8 Roadster - show project
1970 VW 411L Auto - show/restoration project (sold)
1982 BMW 518i E12/8 - stolen
1987 Mazda 323 1.5 SL - daily driver, backup show car
If there is a code for camshaft sensor then put a new one in, as to the Maf a bad one will result in bad running at low and medium revs, cleaning the Maf with electrical cleaning spray is worth a try but in my experience if its gone bad replacement with an oem Bosch or Seimens make is the way to go. Yes a oem Maf is expensive but if yours is duff then you are not going to get it right without hurting your pocket.
I already cleaned the MAF a couple times.
Anyway, I visited the two scrapyards that are left here in Vanderbijlpark, neither one could help (I wanted to test before I buy).
1999 BMW Z3 2.8 Roadster - show project
1970 VW 411L Auto - show/restoration project (sold)
1982 BMW 518i E12/8 - stolen
1987 Mazda 323 1.5 SL - daily driver, backup show car
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