This is the regular B230FT engine, California. No EGR as far as I can tell. Needs gas at start up, then idles a little slow, but runs well once it is warmed up.

I'm showing these codes:
232 Burn-off cleaning of MAF wire not operating, and
322 O2 sensor not operating.

I replaced the O2 sensor and reset the codes. Rough idle at start-up is unchanged (actually worse; it didn't need gas before), and both codes come back. O2 sensor is getting battery voltage to heater circuit.

I'm curious about the MAF burnoff issue. I have swapped out three MAF's ("original", wrecker, and new aftermarket) with no discernable difference. I had some more serious issues that I finally traced to weak fuel pressure--now corrected.

Any suggestions will be welcomed, and any thoughts on how to address the burn-off non-operation.

 

This may be a stupid question, but do you have the right MAF, ie same parts number (for LH2.4). I would make sure that the contacts in the plug that goes into the MAF have not been pushed back into the plug. I've heard that they can get pushed back and then not make contact. Same with the O2 sensor. Give that a shot.

 

I've looked at the connections at the MAF and also at the ECU and used the side pin access to try to slide the ECU connector terminal out a bit. Also sprayed the ECU and MAF terminals with a two-stage contact cleaner/conditioner (Deoxit DN5 and GN5).

The other, rather major, discovery was that the timing belt had slipped a notch. I don't know how long that's been off but the improvement in power a driveabillity is great!

So now after a few days I'm showing no codes and I'm loving this car again. Cold start stall out and idle speed variation is still happening though, and after switching out the Idle Air Control with a wrecking yard unit and seeing absolutely no difference, I'm wondering if:

a: The Engine Coolant Temperature sender is bad (I'm getting 2235 ohms at about 65 degrees which seems on the low side--spec is 2350 - 2750 at 68 deg. and shouold be higher at lower temps.
b: The MAF wire has sustained damage from apparently not getting a burn-off signal while I've been working through this.
c: I have an accumulation of carbon in the combustion chamber/valve are that should be cleaned out with some fuel additive.

The MAF is the correct one, and given that I'm not getting codes I'm leaning to "a". It looks like the only way to access the ECT sender under the cylinder 3 inlet is to remove the manifold. Any tricks that would avoid this?

 

your ECT is close enough for jazz, if it was 1000 or 4000 ohms, I'd be worried.

re: your idle problem, make sure the idle switch on the throttle is working fine (I'd use an ohm meter across the contacts while manually moving the throttle position, car off)

a california turbo certainly should have an EGR. see this picture,


which is a 1991 940SE turbo. over on the far right, between the strut column and the power steering reservoir, there's a funny little thing with the two vacuum hoses coming off? thats the EGR vacuum controller. if you have this, you have EGR.

this picture is a 1992 745T, and things are a bit moved around, but the EGR controller is just to the left of the strut tower, and to the right of the ABS controller...



one vacuum hose goes to the intake manifold vacuum tree, and the other goes to the EGR actuator down under the intake manifold. there's an electrical connector on the bottom of the EGR vacuum controller, it switches the vacuum on/off. there's various ways to test this system, most involve using a mity-vac.

 

Pierce:
I'm glad you're steering me away from the ECT sensor--I didn't want to do that job anyway! I've tested the TPS idle position using the "Control Function 2" test procedures, and it checks out fine. I'll take your suggestion though and test the open-circuit resistance tonight when the engine cools off a bit.

As for the EGR, I don't seem to have any of the components, and no take-off for exhaust gases on the hot side of the engine. The 780 engine bay (photo) is a bit different from other models and I've had to search widely for some electrical parts. But a thorough search fails to reveal any EGR bits. I'm wondering if the 780 being low volume and sourced from Italy fell into some waiver category. Doesn't sound like California, but this was definitely a Cali car from the start.

I also now have my 322 and 232 codes back again (MAF burn-off and O2 sensor), so I'm not feeling the love like I was for a bit there. The O2 Sensor was replaced with new in the course of this exploration and made no difference. Likewise the MAF. I have continuity on the MAF burn-off wiring between ECU and MAF connector, and the ECU was checked for this signal, so the codes are increasingly looking like indications of symptoms rather than causes. Today I checked injector resistance and got 3 ohms across the board (hot engine). I'll recheck these too when it's cooler. Chiltons says 2 ohms for turbo injectors.

Any other idea? I'm open. Actually it has also occured to me that there could be valve damage so I'll work on getting a compression test soon.

 

check for power on the two wire connector to the O2 sensor, should be +12V and ground there (unless its a 1 wire connector, then use chassis ground), so a volt meter would read 12V across the two when the ignition is switched on and the engine is running. I believe the +12 is on a pink wire (ok, I'm looking at the wiring for a 1991 740/940 turbo, so I could be wrong here), and its only on when the fuel pumps are running so the engine has to be running to see this. all the O2 sensors I've seen from these vintage cars, there's two connectors, a round one has the 'signal', and a square one has the heater power, which is what we want to measure here.

power to the MAF comes in on a blue-yellow wire to pin 5, and is the same power that runs the ECU and a pile more stuff. pin 1 (brown wire) is ground at the MAF, pin 2 (blue-green), pin 3 (blue-red) and pin 4 (blue-white) all go to the ECU


btw, the above wiring is the same on the 1991 940SE which is for all practical purposes a 960 Turbo neé 760 Turbo, and your 780T is basically a 760T. here's a series of pictures I took of the engine compartment of a rather dusty 1991 940SE just before I sold it. http://pierce.smugmug.com/Misc/1991-B230FT-940SE/ ... in 1992, things changed some, a larger radiator, different turbo plumbing, dfifferent overflow bottle, various other subtler changes. here's a 1992 745T/945T... http://pierce.smugmug.com/Misc/1992-B230FT-740-Turbo (my daily driver)


btw^2... I wouldn't trust Chilton's to prop the shop door open.

 

Pierce:

I agree on Chilton's. What would you recommend?

The TPS checks out with about 0.6 ohms at idle and then open circuit when the throttle is moved off the stop.

The injectors all come in at or about 2.6 ohms on a warm engine, and since they all seem to be the same I'm going to conclude they're all good.

The voltage to the O2 sensor reads 12.72 V (battery voltage).

Likewise the power supply to the MAF. I believe the burn-off signal goes to terminal 4. I'll need to check that when I have a spare body to shut down the engine while I watch for the voltage spike.

More tomorrow, maybe... Thanks for the input.

 

the best resource is the volvo greenbooks. VCOA sells a series of DVD's, one each fro the 2x0, 7x0, 9x0 cars, I have the 2xx and 9xx disks, they are $65 each. these have a fairly complete set of greenbooks scanned onto them, but are rather copy protected so they can only be used on one computer, and can't be screenprinted (you CAN print a hard copy of select pages, but these printouts are watermarked)

 

All problems now resolved and this sweet ride is running smooth and swift. The love is back and my 780 Bertone turbo is ready to deliver on all my expectations (I hope!)

In the past week I had decent running, but was still getting the same codes as I had at the start of this saga - 121, 232, 322 - pointing to the MAF signal, the O2 sensor, and the MAF burnoff.

Starting to drive home after a 2-hour stop about 40 minutes away, the turbo charge-air outlet hose blew off. This had been in place since installed by the previous owner (~10K miles ago), but the T-clamp was too big for the job--it had been tightened to its mechanical limit and was evidently not quite tight enough. I don't think this had anything to do with my other problems, and the codes still came back after new clamps and hose.

I have changed out the TPS for a salvage yard unit that showed about 1900 ohms beween terminal 2 and ground (terminal 18). The old one showed about 600 ohms (not 0.6 ohms as reported above) in the car but when I took it out I got almost zero. For the turbo, it's only the idle setting that matters--it doesn't use a full throttle signal. The diagnostic tests using the OBD had all checked out fine. This improved the performance noticeably, but the codes still came back and I still had a stall on cold starting, but easily overcome with a little throttle for a couple of seconds.

I installed a clean air filter (the old one wasn't particularly dirty, but with the few miles driven may have been more blocked than it appeared) and replaced the new MAF with the original (3-yo) one, re-seating the airbox and making sure everything was kosher. The cold start the following morning (today) had no stalling, but after five or ten seconds at idle the speed started to fluctuate, 750-800 to start with, building to 700-850 over another 20 seconds or so. However, no codes!

Today I went back to the junkyard and got an idle air control that has steadied the idle speed. I had tried this before, but it made no noticeable difference, probably because the other malfunctions masked this effect. The car runs great--better than when I bought it--and I plan to take it to Sacramento this weekend, a round trip of about five hours.

It now seems to me that all my issues could have come from a weak fuel pump (32 psi instead of 42 psi), old air filter--maybe three years even if only about 10K miles--a dodgy idle air controller, and a weak signal from the TPS. I remain troubled that this doesn't explain the sudden onset of driveability problems, unless from a sudden drop in fuel pump performance or from a TPS failure that exposed weaknesses in other systems or components.

I will be happy to hear other inputs.


Recapping the whole saga this is what I would do again in a similar situation in future:

1. Test Fuel pressure early, don't just confirm the operation of the pumps.
2. Don't rely on the appearance of the air filter. If the engine isn't running well, replace the filter. A fouled filter may be causing or exacerbating problems. If running rough, take off the front cover and double-check valve timing.
3. I now have a sturdy digital multi-meter, and I am accustomed to the ranges, and response times.
4. Check supply voltages to all applicable sensors and components.
5. When resistance-testing components, remove them from the vehicle where possible. Alternatively some resistance and voltage tests can be done at the Engine Control Module.
6. Don't rush into buying new parts. Having access to parts from salvage yards or similar models in good order helps eliminate possible causes. Take the Voltmeter/Ohmeter and Manual to the salvage yard to test components to known standards.
7. The OBD-I system, if equipped, can be deceiving. Codes can get you working on symptoms rather than causes. I bought a new O2 sensor and a new MAF. It seems I didn't really need either. The original MAF (3-yo) is back in the car, the O2 sensor is new, but made no difference. So now I have spares!
8. A model specific greenbook would be a helpful start. I sometimes found I had spent ten minutes reading about a Regina diagnostic procedure when I needed to be on the LH-Jetronic pages.

This was a great learning process for me, and I am now much better equipped to do my own diagnosis and keep my Italian Viking running smoothly.

If everything checks out on the Sacramento trip, I'll be moving on to replacing universal joints and the hanger bearing.

That's all folks!

 

You might have a bad computer...or wiring

 

this is a 3 year old thread.