B21 Kjet low idle, no power, '78 242

I can't drive it now after starting it with a fuel injector put in a bottle to test it. I started it and it ran for a few seconds, made a loud pop and now it barely runs. No idea wtf happened but now it's undrivable
Idle AFR is in the 15 to 16 range before that.
It has a new stock 02 sensor, my AEM wideband has it's own bung.
Fuel pressure has been fully tested according to Volvo Greenbooks, but that did not include driving
Full ignition tuneup
Both fuel pumps are new this week, stock style units
Cam timing is correct, one of the first things done
There are voltage drops at the fuel pump relay. It measures in the high 11 VDC area. Has not been measured at the pump.
Wish I could measure the fuel pressure while driving but it barely runs now. Installing my LS motor might be easier at this point lol.
I can check compression, put it on the list...

2turbotoys said:

I can't drive it now after starting it with a fuel injector put in a bottle to test it. I started it and it ran for a few seconds, made a loud pop and now it barely runs. No idea wtf happened but now it's undrivable
Idle AFR is in the 15 to 16 range before that.
It has a new stock 02 sensor, my AEM wideband has it's own bung.
Fuel pressure has been fully tested according to Volvo Greenbooks, but that did not include driving
Full ignition tuneup
Both fuel pumps are new this week, stock style units
Cam timing is correct, one of the first things done
There are voltage drops at the fuel pump relay. It measures in the high 11 VDC area. Has not been measured at the pump.
Wish I could measure the fuel pressure while driving but it barely runs now. Installing my LS motor might be easier at this point lol.
I can check compression, put it on the list...

Click to expand...

Can you take a video of it running?

I can after I get my parts, might be a couple days. I didn't bother putting the crusty injectors back in because the seals don't look good.

The charcoal canister is fine, but the drain on the bottom was totally clogged with some kind of bug nest. After closer inspection blowing through any of the lines will not work as a test. The larger line on the canister goes to a vacuum operated check valve, then on to the intake. Those lines are clear. The smaller line comes from the balance valve in the rear which is also something you can't blow through from the front of the car. It may be fine now, but have to wait for
injector reassembly to know for sure.

2turbotoys said:

The charcoal canister is fine, but the drain on the bottom was totally clogged with some kind of bug nest. After closer inspection blowing through any of the lines will not work as a test. The larger line on the canister goes to a vacuum operated check valve, then on to the intake. Those lines are clear. The smaller line comes from the balance valve in the rear which is also something you can't blow through from the front of the car. It may be fine now, but have to wait for
injector reassembly to know for sure.

Click to expand...

? worked on my 79?/?.. Perhaps my balance valve is bad and I didnt know it..? Weird.
It was a while ago, I may have disonnected the line at both ends now that I think about it.
I didnt blow through the under hood stuff, I just replaced it with all the other under hood lines. I didnt want to replace the long run to back of car stuff if I didn't have to.

Or maybe my balance valve is bad? Maybe I should be able to blow through it from the front. I don't know, but based on the attached pic it looks like you should be able to blow through it either way. The under hood line to the intake is fine, I unhooked both ends and blew through it.

EDIT: after running the fuel pump, removing the gas cap vacuum noise does not happen anymore, so hopefully I finally fixed 1 problem haha. Anti bug measures taken, see bottom pic.

New injectors and seals are in. New fuel pump relay, and ran the actual fuel pump power through another relay so I can stop buying fuel pump relays. I now own a dwell meter and compression tester, I will try the compression tester next I guess.
Idle is now worse, about 200 RPM and it doesn't like to be revved, falls on its face unless it's very slow rev.

Here's a kind of crappy video, this is the second one I took, the first I messed up, but it ran even worse for that one. Maybe the small amount of heat it got from that helped, idk.
https://www.youtube.com/watch?v=HipE--nuAzg

EDIT: compression is 119 for every cylinder

What should be my next step?
I kinda want to turn the idle up a bit, and turn the fuel adjustment screw to make it a bit richer like Dmann said, but a bit nervous about making a bigger mess. I don't know how the dwell meter helps or what to do with it but I got one, the fuel adjustments in the greenbook uses the dwell meter and a CO2 sensor which is a really hard tool to find. and the bung is way too screwed up to use. Is the wideband a half decent substitute? I am not concerned with emissions, just running well.
Thanks for all the help guys, this is my longest running "please help me" thread ever, and I really appreciate all the advice.

How did you conduct the compression test? Did you prop open the throttle plate? The 119 reading is lower than any running engine would be expected to produce. Something above 130 psi at a minimum. Better above 140.

I didn't prop it open, and the engine was cold. I didn't know I should have until looking up what the #'s were supposed to be. At that point the battery was really low and I didn't get a chance to redo the test. I figured consistent numbers was a good thing at least. I'll redo it today if it stops raining, still gonna be a cold engine though.

Those early B21's had a relatively low CR, something between 8.5 and 9 if I remember right. Big numbers should not be expected.

Haynes manual says CR is 7.5. But with warm engine and throttle wedged open its supposed to have a minimum of 128 psi, max 180 if I remember correctly. I'll redo the test with cold engine and throttle open, lots of rain and a tornado warning so it might have to wait til tomorrow

Assuming the compression is good (I think its fine because of even #s), which I will figure out tomorrow, what would be my next step?

Personally, I am not thrilled with the 119 psi compression test but it does run. Squirt a half ounce of oil into each cylinder and test again after spinning the engine. Then do a leak down test to determine the valve situation.

Educational references.

Review:

It runs on CIS fuel but that doesn't confirm timing, or vacuum.

About the final thing with the CIS is the dwell. I hope I get this about right. The adjustment of the dreaded fuel trim screw is to get the mixture within the range of the adjustment of the O2 sensor, the ECM and the frequency valve. The sensor, ECM and frequency valve should then manage the mixture to about the ideal 14.7 ratio.

With the frequency valve disabled the 02 sensor swings based on the real natural mechanical ratio of air to fuel. Adjustment of the trim screw centers the mechanical adjustment to that optimum value. Once you get that within about the 45% range and re couple the entire system it should manage itself from that point forward.

Note that the orfice where the 3mm Allen wrench is inserted is also a vacuum leak when the wrench is removed. It is also with the wrench in place but that is close enough. Bottom line: close that little port when finished with the adjustment. I just used an appropriately sized screw.

I hope I got that about right. Criticisms appreciated since I am about to go through that for about the 20th time on the Bertone.

There are so many vacuum ports on these systems that you can never be sure that all are working as intended. I replaced all the 38 year old hoses on mine just to be sure that I did not have a split and they were all in place. In fact, it took me more than a year to find a correct vacuum hose chart for my car. The decal on the inside of the hood was wrong.

In this time frame all the car and subsystem manufacturers were scrambling to meet the US EPA requirements. The fact that my hose chart did not match what was installed is an example.

2turbotoys said:

...Idle is ... about 200 RPM. Video:
https://www.youtube.com/watch?v=HipE--nuAzg

Click to expand...

I didn't read the thread, but have a few comments on the video (if not already mentioned before):
- Your idle speed sounds about right -- it's certainly faster than the 200rpm on the dash gauge. If you have a tach/dwell meter, see what it reads.

- What's the scale on your pressure gauge? If it's bar, then 4.5bar is high.

- There's a whistle from your engine when you rev it up (not the belt squeal), maybe a vacuum leak?

- To adjust mixture with a wideband, disconnect the narrowband O2 sensor and tape off the sensor wire (or make sure it can't contact ground). Then adjust the hex screw to get to ~14.3 on the WBO2 gauge. This sets the open loop mixture to a little rich. When the narrowband O2 sensor is reconnected, the closed loop control should adjust it to 14.7 (when fully up to temp).

- I used a nylon ~2" long x 1/4" bolt to plug the adjustment hole. You can shove it in firmly to deform the bottom threads to plug the hole, and the bolt head sticks up enough to make removal easy.

Edit: I posted some videos on photobucket long ago, but I think they've survived. Look through this thread for details: http://turbobricks.com/forums/showthread.php?t=317666&page=2

Edit2: sorry, it looks like only the thumbnails have survived and photobucket has removed the content.

The fuel pressure is correct, in kp/cm^2.
The whistle is the metal cooling fan
I just checked the idle RPM with a tach, its 550 RPM
The belt squeal is bad bushings, I gotta put them in asap, that squeal is really annoying

I looked at all the hoses I could see, but they all seem fine, I should replace them on general principal though. It was very difficult to get the fuel distribution block to throttle body hose back on, the large bulbous one, and its not all the way on the throttle body but it is sealed. The only way I can think of to get the dam thing all the way on is to drop the throttle body, clamp the hose on, and bolt the tb back on.

Thanks for the fuel mix instructions guys! I will try them as soon as I can. Its a bit scary though haha

Hmm, I'd believe 1100rpm idle, but 550 seems too low for your video. Did you have the tach/dwell meter on 4-cyl or 8-cyl setting? If your meter doesn't have a 4-cyl setting, you need to double the 8-cyl readings.

Pressure seems high for fully warmed up, and test valve opened. Bentley lists 3.4-3.8bar for 079, 123, and 128 regulators (and lower with vacuum applied).

[For my old photobucket videos, I was still able to download them from photobucket and then play them, but playing them directly no longer works.]

I tested all the fuel pressures using the Greenbook and the numbers matched up, I can . My tach is set definitely set for 4 cyl, the engine is idling very low, the sound isn't good on the vid. I should have walked to the tailpipe I guess. After it warms up the oil pressure light comes on unless you give it a touch of throttle.

Fuel pressure test results:
Line pressure is correct at 4.5 kp/cm^2
Rest pressure after pumping the pressure back up, shutting off fuel pump, flipping switch to position 3 = 3 kp/cm^2, Greenbook says minimum is 1.7 so that seems ok also.
Cold control pressure: 1.5 kp/cm^2
Warm control pressure: @ 5 minutes 3.3, at six minutes 3.4 kp/cm^2

2turbotoys said:

Warm control pressure: @ 5 minutes 3.3, at six minutes 3.4 kp/cm^2

Click to expand...

OK, is the pressure tester valve closed in the video? ~4.5 kp/cm^2, or ~4.4bar, is too high for warm control pressure.

~4.5 kp/cm^2, or ~4.4bar, is too high for warm control pressure.

Click to expand...

4.5 kp/cm = 60.0 psi. Assuming that is the system pressure that's a little low in my mind but specific to your engine and year. Mine runs 70 psi by spec and actual.

Warm control pressure: @ 5 minutes 3.3, at six minutes 3.4 kp/cm^2

Click to expand...

3.4 kp/cm = 48 psi might be a little high but probably within O2 sensor and frequency valve control range.

Warm control pressure should be about 45psi. The GreenBooks has specific value for your specific engine. Higher than that is running the engine lean.

About time for the dwell adjustment.

EDIT: Next post provides actual WUR regulation chart with 50-55 the specified value. That is a little on the rich side but probably within range of O2 control.