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1990 740 GLE 16V. Check engine light, rough start and low rough idle. Intermittent crank-no start.

bobxyz said:
Pins are 2.8mm wide by 0.8mm thick.
Click to expand...

I got my test probes in the mail. I was just in the garage and confirmed the male probe fits well in the female terminals on a spare fuel injector connector, and a knock sensor connector on my spare engine.



TestProbes.jpg
 
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bobxyz said:
2-1-3 means the ECU is seeing WOT (TPS WOT switch closed to ground) when at idle/light load. Check the voltage on the TPS pins.
3-1-2 is a problem in the EZK to ECU knock enrichment wire - maybe a poor connection, or maybe poor power/ground to the EZK.
Click to expand...

I am still gettting:

3-1-2: Signal missing for knock-related fuel enrichment

2-1-3: Throttle switch full load setting faulty or grounding short

2-2-1: Fuel trim (lambda control) too lean at part load



I finally accessed both EZK and LH boxes tonight. I used the correct terminal test probe and ALL circuits for the TPS, knock sensor, and the knock enrichment wire between the two boxes tested OK with my Fluke meter. No open circuits or high resistance found on any of the circuits.

I fixed a couple of airleaks in the PCV hose. I installed a new Bosch 02 sensor and I am still getting the same three codes and an inconsistent idle. However, the car always starts and runs at this point.

The LH and EZK boxes both appear to have been swapped out at some point.

I GET A STEADY 0.9V on the old and the new 02 sensor.
 
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Update:

-Replaced broken thermostat and it now gets up to operating temperature normally.
-Replaced broken/brittle PCV hose and put a hose clamp on a torn PCV hose end to curb a large airleak.
-I plugged in a spare knock sensor and it still throws the same two codes, but the fuel trim code didn't pop this time.
-I found a spare ECM with "BAD" written on it in the trunk. The car runs like crap with it plugged in and immediately threw some different code.
-Found the source of the drivetrain vibration: blown tranny mount
-Threw the water pump belt on a test drive a block from home, overheated for about 30 seconds, and coasted into a parking spot and had short walk back to the house with the 12 pack from the back seat.

TornPCVsmallhose.jpgTornPCVlargehose.jpgTornTransMount.jpgTwistedBelt.jpg
 
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I thought the degraded wiring at the Radio Interference Suppression Relay was the only cause of the crank-no-start, but the plot thickens....

Today it decided to do the crank-no-start and it seemed like wiggling the wiring at the RSR relay fixed it, but later on the crank-no-start showed back up. I just got my $5 "injector" noid light in the mail from IPD and it wasn't lighting up with the key on. WTF!? Then I poked around with my $3 test lamp and found I had no power to the MAF, or the control side of the RSR relay. This blue/yellow wire comes from the LH/fuel pump relay and powers the MAF, IAC, and the control side of the RSR relay. I accessed the fuel pump/EFI relay and it wasn't clicking when I pulled/and installed it with the key on. WTF?! I plugged in the "BAD" LH box I had sitting on the floorboard and the relay came to life. The damn "good" LH box wasn't closing the relay intermittently.

Furthermore, I noticed earlier in the day that the LH box wasn't giving me any 1-1-1 code when the car was in running condition. It would not blink anything in position 2. I bet this was the case all along. I was only checking the blinky codes when the CEL was present. I don't think I ever checked for a 1-1-1 when everything was good.

Then, I accidentally shorted out the wiring at the RSR and blew fuse 1 at sunset and that was the end of the day.

SO, I have a new RSR connector coming from Dave Barton website and I have a used "Volvo reman" LH 16 valve box coming. Once I fix the RSR wiring and get a good LH box in there I should have a car that runs consistently and doesn't throw fake codes. Hopefully it will also go into closed loop and I get 02 sensor oscillation.

$3 test lamp, $20 terminal test probes, $5 noid light, and free wiring diagrams (thanks again). These tools have currently lead me to the diagnosis of the issues as:

1. PCV hose air leaks
2. torn FPR hose
3. degraded RSR wiring
4. LH box throwing fake codes and intermittently not operating the LH/fuel pump relay
 
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I got my replacement ECM from ebay today in the mail. I opened it up and WTF!? it had my handwriting on it. I sold the same LH box years ago on tbricks during a B234F part-out and I ended up buying it back randomly.

Anyways, I plugged it in and there was a crank no-start. Uh oh. That didn't fix it. It eventually fired up, but stalled at one point on a test drive and the crank-no-start showed up a few times. Sometimes it will start and barely run. You hit the pedal and it always dies. It seems like it is starving for fuel. I gotta give it the shakedown.

The good news is the "knock enrichment" code and the "TPS full throttle" codes are no longer present. So far, it seems confirmed that the old ECM was throwing two false codes. NOW I have no CEL, but I have a 1-3-1 code (Ignition system RPM signal missing during cranking) I am working on diag. I no longer have the 2-2-1 fuel trim code. Installed new aftermarket elbows on the FPR hose. I have not checked the O2 sensor voltage. The idle is also no longer low and crappy. It is a little bit high out of gear, but in gear, I now seem to have a solid 750 RPM idle. Still working on dialing in the idle.

I rewired the RSR relay and that didn't fix it either.

Gotta figure out the stalling and the crank-no-start, start-runs-like-shit-and-dies issue. If I sit there and crank it enough times, it will eventually start and stay running and become driveable. This is the issue the previous owner was struggling with.
 
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Check the engine speed sensor. See if the wire on it is original by checking to see if it has a yellow tracer. The upgraded sensor uses a white marker on the wiring. Way back in the 90s my moms 245 had this kind of issue. It would randomly happen. The classic situation where it won't start for mom then I try it and it runs and is fine for the day. It finally died in front of the house but never set any codes. The dealer replaced the sensor and it was fine after that.
 
dl242gt said:
Check the engine speed sensor. See if the wire on it is original by checking to see if it has a yellow tracer. The upgraded sensor uses a white marker on the wiring. Way back in the 90s my moms 245 had this kind of issue. It would randomly happen. The classic situation where it won't start for mom then I try it and it runs and is fine for the day. It finally died in front of the house but never set any codes. The dealer replaced the sensor and it was fine after that.
Click to expand...

It looks like it has a cheap MTC sensor on it. It passes the visual inspection, but I have a Bougicourd going in.

I fixed the torn trans mount in 10 minutes yesterday and NVH is much better. I used a $20 Febi mount. I want to upgrade from the round style mount to the square style mount that is in the crossmember. I need the crossmember, bracket, and mount.

During the crank-stall-no-start I heard the injectors clicking and I confirmed the MAF was powered up so it isn't the LH/fuel pump relay this time.
 
I swapped in the bougicord crank position sensor today after work in about 5 minutes. So far, the stalling and crank-no-start hasn't shown back up. I drove it around for an hour or so and all seems well, for now...

Also, I get 02 sensor oscillation now and 1-1-1 on both LH and EZK. The idle is still a little bit high in Park and a couple issues of high/low idle in Drive, but for the most part the idle stays pretty solid at about 800 rpms now.

It chirps into second and got sideways in the rain. I may have myself a new daily driver!
 
I got a "I like your car!" from somebody at the grocery store tonight in the gold 744.

I was driving my black 745 Turbo around and a guy pulled up to me at a stoplight and was smiling and taking video of the wagon.

There aren't any Volvo's out here in the Permian Basin of West TX.
 
Congrats! I'm planning on picking up a 90 745GLE (16V) in August - out in Ohio. Issue I will have is locating all the 16V specific timing & balance shaft belts, etc. It's been in a dis-assembled state for about 20years....
 
lookforjoe said:
Congrats! I'm planning on picking up a 90 745GLE (16V) in August - out in Ohio. Issue I will have is locating all the 16V specific timing & balance shaft belts, etc. It's been in a dis-assembled state for about 20years....
Click to expand...

A lot of the balance shaft stuff is NLA or stupid expensive. A delete may be the best way to go. I deleted them on my last couple B234F+T's and they were fine without them. Luckily my engine is a factory replacement/reman and isn't puking oil. 1990 "should" have the spring belt tensioner (like the 8V) and not the hydraulic tensioner (like 960). I could be wrong. I don't know what is under the covers on this engine yet.

The high rpm section of the 16V is so much fun. Once the engine is revvd up to 4k, it just wants to keep going.
 
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