Smokey 1989 (8 valve) 740 B230

[Volvoaus]

Just fixed the non-start issue on 1989 - 740 B230 (dead in-tank fuel pump) and was running beautifully for 60km (37miles) now I have:
1. black smoke out of the exhaust
2. rough idle
3. I put a 300ml bottle of injector clean in full fuel tank prior to smokey issue emerging
4. During in-tank non start problem I fitted a pink label 561 ECU. Will refit the white label 951 and see if it makes a difference

What makes this problematic is we have Covid lockdown in Melbourne and cannot travel more than 5km from home
Thoughts?

[Laird Scooby]

Before you swap the ECU again, disconnect the battery and pull fuse #1, swap the ECU then reconnect the battery and finally refit fuse #1 before trying to start it.

Have you checked the air filter?

During your diagnosis of the non-start, did you touch the throttle butterfly at all, particularly the adjustment of it?
Also have you cleaned out the PCV system? If not, clean it out (flame trap and the small bore stub on the manifold, spray a load of carb cleaner into the hose that runs from the flame trap into the oil separator and also check the third larger hose from the flame trap to the air clear and the stubs it connects to) and if you did clean it, check it again for blockages. It's not unknown for it to get dirty again rapidly after the first clean.

Also clean the EICV and throttle body/butterfly with carb cleaner, check the connections on your Lambda sensor and also the connections on the MAF.

[NI_Volvo_Nut]

Black smoke - too much fuel, which is also causing your other issue

[Laird Scooby]

Originally Posted by NI_Volvo_Nut

Black smoke - too much fuel, which is also causing your other issue

Agreed on too much fuel - but why?

[griston64]

Could it be an ECT issue ???

[Laird Scooby]

Originally Posted by griston64

Could it be an ECT issue ???

Could be but given it wasn't doing it before he swapped the ECU and the ECUs have a habit of dying when swapped, there's a good chance if he refits the original (carefully, disconnecting battery and fuse #1) that will sort it. At least it eliminates something he's swapped if not.

[Volvoaus]

Originally Posted by Laird Scooby

Before you swap the ECU again, disconnect the battery and pull fuse #1, swap the ECU then reconnect the battery and finally refit fuse #1 before trying to start it.

Have you checked the air filter?

During your diagnosis of the non-start, did you touch the throttle butterfly at all, particularly the adjustment of it?
Also have you cleaned out the PCV system? If not, clean it out (flame trap and the small bore stub on the manifold, spray a load of carb cleaner into the hose that runs from the flame trap into the oil separator and also check the third larger hose from the flame trap to the air clear and the stubs it connects to) and if you did clean it, check it again for blockages. It's not unknown for it to get dirty again rapidly after the first clean.

Also clean the EICV and throttle body/butterfly with carb cleaner, check the connections on your Lambda sensor and also the connections on the MAF.

Thanks Laird Scooby - that ECU stuff is a classy reply (I would definitely disconnect the battery beforehand). The fuse swap sounds great

a. The air filter is practically brand new and still clean
b. Have not touched the throttle butterfly (to frightened to, if you don't understand it, don't go near it)
c. PCV/hoses cleaned/flame trap renewed about 10k (6500 miles) ago
d. I didn't clean the small bore stub on the manifold but will reclean all these
e. The rear main seal is gone so all your PCV comments make sense
f. If the Lambda sensor is the one down on the exhaust pipe, I cleaned it a while ago with the correct sensor spray (and didn't attempt to wipe)
g. Will clean the idle control valve (EICV) & MAF connections

Is an idle control valve clean just the connections or can you rip the guts out of it?

[Laird Scooby]

Originally Posted by Volvoaus

g. Will clean the idle control valve (EICV) & MAF connections

Is an idle control valve clean just the connections or can you rip the guts out of it?

Pull the inlet hose to the EICV (idle control valve) off the valve body and give it a seriously good squirt with carb cleaner. Refit the hose and start the car - you may need to give it a few revs to help clear the gunge out. Now pull the inlet hose off the EICV again with the engine running, stick your thumb in the end of the hose so you don't confuse the MAF too much and give the EICV another good squirt or several gentle squirts but be prepared to catch the revs if the engine falters.

That should make sure it's all clean as the clean without the engine running cleans the valve when it's closed and with the engine running, cleans it as it opens and closes.

Throttle body similar, remove the inlet hose with the engine off, give a good squirt on the throttle butterfly, opening it by hand to squirt further in around the drillings near it and the edges of the butterfly, refit the hose and start it, giving a few revs to clear the gunge that gets dissolved by the carb cleaner. Small bore stub on the inlet manifold that goes to the flame trap, pull the hose off and inspect it, should be clear. If in any doubt use a small drill bit (3mm from memory) in your hand to clear it with a clockwise turning motion then a squirt of carb cleaner to get the bits you missed - likewise the small bore hose on the flame trap.

As i mentioned earlier, it's not uncommon for the PCV systems to clog up again after being cleaned, especially if oil/filter changes have been neglected in the past or skimped on and perhaps the PCV system hasn't been cleaned at any time in its life. THis means there is gunge that is disldged by the first cleaning process that then goes and blocks the freshly cleaned system. These days i usually suggest people do a clean and then a month later, clean it again to make sure.

[Volvoaus]

Problem partially solved for the moment:
1. Removed the idle control valve (ICV), in/out hoses and gave them all a good carb cleaner hit, including the electronic connection (with electronic connector spray) - No start

2. Now running rough & smokey. By the time I got to the engine bay, pulled the ICV inlet hose off and whacked my thumb over it stalled. In between start attempts I squirted carb cleaner into the ICV - no start.

3. Swapped the evil pink label 561 engine control unit (ECU) over for the more reputable 961 ECU. Still smokey with barely any accelerator response. – no start

4. Gave butterfly/small/medium/large bore brass stubs a good clean (the flame trappie one was bit blocked) – no start

5. Gave the MAF connections a squirt of electronic connector spray (was already good). – no start

6. The air filter is pristine – no start

7. Removed PCV and all accoutrements (including flametrap). Having done this job about 10k (6k miles) ago they were all fairly clean. Cleaned them anyway – No start

8. While waiting things to dry, for entertainment, I attacked the missing 12mm (half inch) stud on the red heater pipe bracket located on the block under the exhaust manifold. That was fun. I incorporated the ‘mechanics third eye’ and was keen to crack open the champagne when I finally got that stud turning 1/16 inch per turn.

9. Last job for the day was sensor spray on the exhaust sensor located under the driver’s compartment (right hand drive car). It started

10. At least now running. Still smokey. Not sure if fuel injector cleaner is contributing to this issue
Suggested to my son the Covid lockdown demonstrators in Melbourne should all get themselves a Volvo because that will keep them occupied/distracted

[Volvoaus]

Black smokey exhaust finally resolved (at this stage). Not sure what finally fixed it, but I additionally removed the ECU temperature sensor (19mm deep socket - above the PCV), multimeter tested it in ice cold water - boiling water and found there was more resistance then a bunch of WWII French partisans.
Possibly what may have resolved the issue was a full removal of the throttle (butterfly) body and complete clean. Cleaning insitu means its only getting half cleaned. Now whats next?