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Old 05-24-2020, 05:48 PM   #1
djkib
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Default 1986 LH2.2 240 idles perfectly but...

All,

I have scrubbed all the Volvo boards I could find for my run condition, but could find nothing that might help me understand what is going on with my 1986 Volvo 240, LH 2.2, Automatic transmission.

I just bought the car, and have plans to add a turbo, but first want to get all possible gremlins out before throwing the speed parts at the car. Engine plans include turbo, megasquirt, manual trans, limited slip, one-piece drive shaft, etc., but want to drive the car for a wile to make sure there are no other major issues.

I also have a 1987 240 LH2.2 5 speed car, that runs perfectly. Referred to below as "DD". Below, where I say I "replaced from my DD" - I literally swapped parts, then tested my daily driver. All parts moved seemed to work perfectly on my daily driver.


The symptoms:
  • Car idles perfectly, right around 800 RPM
  • Car revs perfectly in park/neutral
  • Drive the car, at around 1900-2000 RPM, engine cuts out - falls flat on its face. Tach drops to about 1000 RPM (I'm assuming that is about where the converter stalls?). The car is still running, however...
  • Take my foot off the gas then re-apply gas, car comes back to life until it hits around 2000 RPM.
  • Anything over 2000 RPM is run for a second, then cut out... take my foot off the gas, then run for a few seconds, then cut out. One time, i got it over 3000 RPM and it ran perfectly for over a minute... One time. I have not been able to reproduce this.

So far, here's what I have done:
  • Installed the tach out of my DD where the large clock used to be
  • New Fuel Pump - Authentic Walbro GSS340 in the tank (replaced hose to filter with high pressure fuel injector hose)
  • Removed in-line pressure pump - taped the electrical connectors to prevent inadvertent arcing to stuff under car
  • New fuel filter
  • New fuel pressure regulator
  • Replaced MAF (AMM?) with known working from my DD
  • Replaced Ignition Control Unit with known working from my DD
  • Replaced Engine Control Unit with known working from my DD
  • Replaced the distributor with known working from my DD
  • New/different wiring harness from a known working car (not my daily driver). Continuity between all points verified before installing (what a pain).
  • Replaced the coil with known working from my DD
  • Tested throttle position switch per instructions on brickboard. Verified it is adjusted to "click" as soon as the throttle is cracked, and another click near WOT.
  • Verified no vacuum leaks with carb cleaner test around all ports/hoses
  • New cap, rotor (bosch), wires (bougicord) and plugs. Old plugs were not fouled, nice tan insulator, but electrode was consumed.
  • Base timing set to 12 degrees BTDC

I'm stumped. Please help... I don't have much hair to pull out anymore...
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Old 05-24-2020, 06:34 PM   #2
mschultz373
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i'd check the grounding wires off the main engine harness. check ignition harness ground wire. if the ground is loose, maybe the excess vibration from higher RPMs while driving is causing an intermittent problem.
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Old 05-25-2020, 07:14 AM   #3
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What is the fuel pressure at the rail?
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Old 05-26-2020, 09:17 PM   #4
djkib
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Default Saga continues...

Sorry for the hiatus - holiday weekend - took the "new" car - 2002 v70xc... the wife's car...



Before I go further - THANK YOU to all who have served and continue to serve in the armed forces, police forces, first response units, fire units - all who run TOWARD danger when others are running away - I thank you for all you have given, continue to give, and those whom have given all.



@mschultz373 - thank you - all grounds have been checked and verified tight and verified continuity using continuity test on volt meter. I even used the "wiggle test" while idling - no wiggling of any wiring changed the run condition of the idling motor, nor did it change the symptoms when test driving at any point.

@cleanflametrap - thank you - fuel pressure at the rail... 30psi at idle with the vacuum line hooked up to the fuel pressure regulator, 40psi at idle with the vacuum line disconnected and plugged. Test drove with the FPR vacuum connected and disconnected - had no effect on the symptoms.

Also verified ground at fuel pump is good (in the trunk - brown wire), and 12.4 volts between the pump power line and the pump ground screw.

Latest testing included:
  • Drive with fuel pressure gauge hooked up - fuel pressure did not waver - under load, throttle open, still read around 35psi, no wavering just pressure following vacuum signal
  • Drive with old-school timing light hooked up, and timing "gun" in the car - never lost spark - flash frequency dropped as engine RPM dropped, but I expected that (as the engine lost rpm, rotor in the distributor rotated slower, dropping the frequency of the flash of the timing light)
  • Drive with volt meter positive back-probed to green/white wire on the fuel injector and negative on ground near the fuel injector ground - voltage did not follow the symptoms - fluctuated between 9v and 11v.
  • Drive with volt meter positive back-probed to yellow/red wire on the fuel injector and negative on ground near the fuel injector ground - voltage remained rock steady at 12.4v.

Still open to suggestions...
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Old 05-26-2020, 10:07 PM   #5
mschultz373
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maybe connect the volt meter in series to the in-tank pump and verify current draw is in spec. I think it's typically ~3amps current draw depending on the unit.

maybe check fuel delivery volume , too?

and coolant temp sensor. that's listed as possible cause of poor engine power in bentley manual.

when you drive it, does it die at 2k rpm and NOT get above that? so it won't go above - i'd guess- 2nd gear or so? or is it intermittent?

troubleshoot the ignition system components to verify they're all good, too?
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Old 05-27-2020, 03:26 PM   #6
djkib
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Quote:
Originally Posted by mschultz373 View Post
maybe connect the volt meter in series to the in-tank pump and verify current draw is in spec. I think it's typically ~3amps current draw depending on the unit.

maybe check fuel delivery volume , too?
Please see above - brand new walbro GSS340 255lph in-tank pump providing volume and pressure - also above are current fuel pressure at the rail, and tests with vacuum hooked-up and not-hooked-up to brand-new fuel pressure regulator.

I will try to run a volume test tonight.

Quote:
Originally Posted by mschultz373 View Post
and coolant temp sensor. that's listed as possible cause of poor engine power in bentley manual.
I get good coolant temps on the dash gauge - with and without the temp compensation board.

Quote:
Originally Posted by mschultz373 View Post
when you drive it, does it die at 2k rpm and NOT get above that? so it won't go above - i'd guess- 2nd gear or so? or is it intermittent?

troubleshoot the ignition system components to verify they're all good, too?
Also, please see above related to ignition system components - ICU, ECU, distributor, cap, rotor, wires (bougicord) swapped from known good car.

the issue is 100% repeatable - drive down the road, hit 1900 rpm, and it falls flat on its face under acceleration. If i slow down such that i am under 2000 rpm, car runs perfectly. The transmission shifts fine - i can get above 40-45 mph under 2000 rpm.

I was also able to repeat my success at driving the car above 3k rpm by downshifting until over 3k, flooring it, and it didn't stutter at all. Getting above 3k was the trick.
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Old 05-27-2020, 03:28 PM   #7
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Lean will cause this.
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Old 05-27-2020, 08:20 PM   #8
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You don't need to do any more with fuel delivery given you can watch the rail pressure hold when the issue arises.

Guess my next check would be to watch the O2 sensor looking for that lean condition ZVOLV mentions. Or disconnect the cat? Please pardon me if I missed these in the post.
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Old 05-29-2020, 07:32 AM   #9
djkib
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So, i was evaluating the O2 sensor last night. Looks like the previous mechanic had similar thoughts.

The green shielded wire has been fooled around with. Gone is the big plastic connector, and about 3" of the wire. What does this wire do?

I am soaking in pb-blaster and will test per previously posted instructions on how to test an O2 sensor.

Thanks again to all the pointers - much appreciated!
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Old 05-29-2020, 07:57 AM   #10
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The shield just helps protect the circuit from EMI (interference) from other components such as the ignition wires. I wouldn't be too worried about it, but a pic would help.

You could get a needle probe, or even just a paperclip, and BACKPROBE the signal wire for the O2 sensor. The white wires are just the heater circuit. NOTE: ONLY BACKPROBE connectors, or use a correct probe to frontprobe a terminal. Don't go stuffing a $5 meter probes into the front of terminals; it will spread them out.



I just know that failure to rev is usually ignition timing is pulled way back, or lean. LH 2.2 is VERY sensitive to air leaks. Spray around with brake cleaner and see if you can get the engine to run differently. WIGGLE TEST the wiring harness also.
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Old 05-29-2020, 05:59 PM   #11
djkib
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Quote:
Originally Posted by ZVOLV View Post
The shield just helps protect the circuit from EMI (interference) from other components such as the ignition wires. I wouldn't be too worried about it, but a pic would help.

You could get a needle probe, or even just a paperclip, and BACKPROBE the signal wire for the O2 sensor. The white wires are just the heater circuit. NOTE: ONLY BACKPROBE connectors, or use a correct probe to frontprobe a terminal. Don't go stuffing a $5 meter probes into the front of terminals; it will spread them out.



I just know that failure to rev is usually ignition timing is pulled way back, or lean. LH 2.2 is VERY sensitive to air leaks. Spray around with brake cleaner and see if you can get the engine to run differently. WIGGLE TEST the wiring harness also.
Understood - i am no stranger to electronics... thanks for the reminder, though - might help others too...

I have wiggle tested virtually everything under the hood, no effect.

I have also used starter fluid around all intake hoses and vacuum lines - no effect.

When i tried to pull the connection to the signal wire from the O2 sensor to the harness (single wire) apart, the connector on the green wire (harness side) came off in my hand... I crimped a new one on, making sure to not crimp any of the shield strands into the connector.

I plan on swapping the O2 sensor onto my DD car... I will have more results later this weekend. Right now, though it's pouring buckets... so... beer me... it's Friday night...

Cleanflametrap - i have not disconnected the CAT yet... but it is a thought... don't think the neighbors would like me very well, though...
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Old 05-29-2020, 07:43 PM   #12
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I didn't see it mentioned, so any chance the intake hose or something in the air box is getting sucked shut and cutting off air to the engine?
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Old 06-02-2020, 12:52 PM   #13
djkib
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I didn't see it mentioned, so any chance the intake hose or something in the air box is getting sucked shut and cutting off air to the engine?
I thought that too... Intake track is clean. all my testing is done with a brand-new air filter in place, and i have even removed that. All intake hose have been verified not-broken, not collapsed, and the intake air box has good open path to "outside air".
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Old 06-04-2020, 02:43 AM   #14
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Can you rev past 2k in drive with the wheels off the ground?
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Old 06-04-2020, 10:47 AM   #15
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Quote:
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I get good coolant temps on the dash gauge - with and without the temp compensation board.

The ECU has its own temp sensor, separate from the one that drives the temp gauge. But you'd probably have cold and/or warm start issues if that was bad.
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