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Old 07-13-2020, 03:13 PM   #1
mschultz373
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Default Righteous Gremlin - dying, no start

i have now had 2 occasions in the past month where my 85 240 has died while driving, cranked but failed to start for a period of 5-15min, then started and seemed to operate normally.

the first instance happened ~3hrs into a 12hr trip about a month ago. the car died on the highway while idling in stopped traffic, would not turn over for 15 min, only to suddenly turn over, drive normally and successfully complete the remaining 9hr trip of highway driving, averaging 70-75mph, starting normally after getting gas, etc.

the second instance happened just today. i had not driven the car in two days. i got a block from my house when the car died. I coasted to the side of the road and it would crank but not start. after 5min - poof! - it starts up and i drove home.

here's what I got for diagnostics:
- engine wiring harness replaced with D Barton harness in June of this year
- my battery is 12.6V static, idling at 13.6V unloaded. brushes are in spec.
- IAC resistance measurements are in spec. unplugging IAC did not make a difference during no-start condition.
- MAF resistance measurements are in spec. unplugging MAF did not make a difference during no-start.
- in-tank fuel pump drawing 3.1A current, battery voltage present
- main fuel pump will turn on and run jumping from fuse 6 to fuse 4 trick. sounds maybe a bit harsh - it's not purring, let's say.
- fuel pump relay replaced with new unit in late March of this year
- ignition system troubleshooted and checked out in June of this year with hall effect sensor replaced

my general thinking is I am chasing some esoteric gremlin. It could be too low fuel pressure or a faulty coolant temp sensor - and I have not checked either as of yet -, but I don't suspect either as a main fault since this no-start condition has only occurred twice in last month in the midst of the car driving normally and completing both a 12hr trip and at least two 3hr round-trip highway trips. not to mention it being my sole daily driver.

any thoughts or advice on what to consider next is helpful. thanks yall.
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Old 07-13-2020, 05:08 PM   #2
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The problem with intermittent problems is you can only troubleshoot when it's happening. What you can do it check the various systems for proper operation. Check connections on cables going to things like the ignition. Make sure ground wires are clean and tight. Go over the connections on the fuel injection sensors and injectors, air mass meter, with sealing greases to keep the connections clean from corrosion.

Check other systems for up to date service like fuel filters. Make sure the air box thermostat is either working properly or delete it. Going over the various systems on the car will probably sort out an intermittent problem especially since many older cars it's an electrical issue.
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Old 07-13-2020, 05:52 PM   #3
mschultz373
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well it's no longer intermittent. I went to leave for a job - car died a block away just like before. finally started, got home and it died right as I turned into drive. not able to get her started currently.

the battery volt gauge in the dash is reading in the low orange zone when cranking. i don't have a helper so I can't read the voltage on the battery whilst cranking. not sure if that's useful or not.

car idled in driveway in P, N, and D without dying. started after sitting ~5min. then could turn off and start several times without issue. I could sustain decent throttle in P and N without dying. NO obvious wiring faults with a cursory wiggle test in the engine bay. My main fuel pump sounds a bit raspy. I remember on cleanflametrap's site reading something about a raucous buzzing pump indicates fault... maybe that is what I am hearing.

I haven't ever looked at the airbox thermostat. I have the heater pipe deleted and it's been 100F+ heat index for three days. not sure if that's relevant.

Last edited by mschultz373; 07-13-2020 at 06:08 PM..
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Old 07-14-2020, 12:58 PM   #4
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not much new to report, it's hotter than hades out so I couldn't get much done before going inside. however:

- car is getting spark, ignition timing is steady at idle, BUT the car did die at idle with tach light attached to battery after ~2-4min. It would not start for a period of time, then started back up and idled strong for ~20min. This makes me suspect some kind of power/battery issue

- ignition coil resistance between 1 & 15 is 1ohm; spec is 1.1-.13ohms. Resistance from 1 to center post is 13.97-14.15kOhms - the spec is 9600-11600ohms. so i wonder if my ignition coil may be the fault? but would a coil fault create this intermittent condition?
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Old 07-15-2020, 11:05 AM   #5
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I had a similar problem with my 87 245. It would idle and rev in neutral but as soon as I put it in gear and went to drive it would die. Wound up being the wiring going underneath the coil was deteriorating and touching together. Patched it up and she’s as good as new
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Old 07-15-2020, 06:33 PM   #6
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thanks for that tip. I'll make sure that wiring is good.

my friend helped me do a bit more diag today and we think it's the IAC or some fault in the idle circuit. In P, the car idles ~28Hz after warming up from ~25Hz - the opposite of what presumably should be happening. Additionally, with the AC on, the P idle drops to 23Hz. We observed the same in D - the car idled ~23Hz and dropped to ~19-20Hz with AC on.

The other clue to this fault is that my idle bypass screw is not affecting the idle at all. grounding the IAC via the test terminal doesn't appear to make any difference either to the effects of the bypass screw. I can hear a mechanical hum when grounding the port, but no effect at all.

my general thinking is to check the bypass channel in the throttle body and make sure the channels affected by the bypass screw are clear and probably replace the IAC. Bentley lists IAC fault as a possible reason for engine failing to start and engine starting then dying, which accords with what I've descrbied.
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Old 08-04-2020, 05:58 PM   #7
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I am reporting back after the car died last night on the highway. Same symptoms - pedal cut out, car shunted/surged like it was intermittently getting fuel, then died. It did not start for several minutes but would start and run normally after ~5min. the only correlating detail worth mentioning is that I did get the car to ~90mph about 10min before the dying.

i have a new IAC just received today so I'll put that in later tonight and see if that solves this issue. but I have a few other symptoms I wanted to mention.

The volt meter in my dash has been erratic lately, usually reading just above the 'red' zone at 10V upon first starting then slowly creeping up to about 55% full while driving unloaded. with lights and radio on, the meter reads about 40%, and with the tail lights flashing, it will dip down to 30%. also, there have been several times where my volt meter reads completely dead during normal operation and will bounce back to 55% with a flick of a turn signal...

at stops, with my left turn signal on and brake on, my bulb failure light will flash with the turn signal as if indicating a faulty turn signal bulb. the car will also idle and sputter during this. I dont observe this with any other light operation.

over the weekend, one night, as I was driving, the charge light and overdrive light appeared to be slowly illuminating - a symptom of blown fuse #13, IIRC. I engaged then disengaged the overdrive and both lights went out.

my battery voltage has been varying over the past month from 13.3V to 14.04V unloaded.

So I don't know what I am chasing. I suspect it is rooted in a circuit off of fuse #13, since that fuse serves the instruments, turn signal, and fuel pump relay. I troubleshooted the fuel pump relay and did not discover any obvious faults; i likely need to check the ECU to be safe. but my hunch is there is some strange interaction between the things powered off fuse #13 and/or the IAC valve. if there is some short or intermittent fault in a circuit that will cause a fault with the fuel pump relay, that would seem consistent with the dying/no start I've described since that relay pins out to fuel pump/pressure reg/engine rpm/ICU/ignition switch. the other symptoms all point to fuse #13 circuits as the culprit(s).

Last edited by mschultz373; 08-04-2020 at 06:07 PM..
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Old 08-05-2020, 03:39 PM   #8
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Wiggle test wiring and connections.
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Old 08-06-2020, 01:54 PM   #9
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Replaced the IAC yesterday with good results. Idle is higher, stronger, and the volt readings are better. Will report back with more at a later date. Thanks yall!
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Old 08-08-2020, 02:37 PM   #10
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car had the condition yesterday that persisted for about an hour. surging acceleration which eventually cut out, then car died. car wouldn't start, then would and would run choppy. she died/started about 4-5 times - I was trying to get a friend to a gig. we got there, car start for a few hours, and since it's operating normally. so IAC, while replacing a fault one, is not the core problem. the only other detail I can offer right now is that the condition is correlated with highway driving in midday heat - we've been having 95-100F days lately. not sure that that would make a difference. going to troubleshoot more today after rain lets up....
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Old 08-08-2020, 03:04 PM   #11
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Quote:
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Wiggle test wiring and connections.
So?
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Old 08-08-2020, 09:09 PM   #12
mschultz373
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no obvious conclusion from wiggle testing ECU, ICU connections nor main wires off the fuse block.

ECU tests all check out EXCEPT for AMM main heated wire reads 2.9ohms, where lh2.2 spec is at least 3.5ohms. other specs of AMM check out. i suppose it could be the actual ECU box failing?

ignition system checks out EXCEPT coil secondary resistance is ~13k ohms, which is higher than limit of spec at 11k ohms.

i doubt either are the problem with the car since it will run normally often enough. i suppose it could be intermittent MAF.... i'm going to have to dig deeper in the wiring off fuse 13 and to the fuel pumps tomorrow to see what I may find.

bentley suggests it could be CO content too low/high (i haven't adjusted it as of yet due to anti-tamper plug) or fuel pressure, which I haven't checked due to not having a pressure gauge. i doubt either are the main issue, though.

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Old 08-08-2020, 10:21 PM   #13
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240 common issues are:

-hall sensor
-Ignition box connections
-cabin fuse holder corrosion
-underhood battery fuse/holder
-"fuel pump"/main relay
-fuel pumps

Maybe rig a test lamp to the various circuits and see if the circuit is down during a no start.
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Old 08-09-2020, 10:17 AM   #14
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Quote:
Originally Posted by ZVOLV View Post
Wiggle test wiring and connections.
^ Yes. I had a similar situation and it was broken main pump wiring where the harness makes a 90* turn and drops through the floor below the rear seat to the underside of the car. Hope you get it figured out
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Old 08-09-2020, 01:04 PM   #15
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no thoughts on the out-of-spec AMM and ignition coil? figured I better replace both since their resistances are off. particularly the AMM, since a faulty AMM would result in dying/no start.

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Old 08-14-2020, 03:17 PM   #16
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I had a few more thoughts on the MAF/coil.

The MAF measures the mass of air coming in via the heated wire. The spec for LH2.2 MAF is 3.5-4ohms resistance. My out of spec MAF, at 2.9 ohms, means a higher current is flowing to/from the heated wire and thus to the ECU. So the question is what the ECU does with the higher reading - does it dump more fuel into the engine since it thinks a larger mass of air is flowing into the engine? This would result in a rich condition, since the same mass of air is moving thru the MAF, it is simply measuring that mass incorrectly. But that wouldn't presumably result in an intermittent dying/no start condition. bentley even indicates that a MAF fault will not cause a no start/dying condition. UNLESS there is some way the ECU would understand the reading from the MAF as a major failure and shut down the car.

Given all of this, I am more inclined to suspect that the ignition coil is the culprit for the dying/no start. since it is out of spec with a higher resistance, less current is flowing through the entire ignition system. But generally it is not an impedance to operation - UNTIL, on hot days and on longer trips, the heat in the engine bay raises the resistance of the circuit and the coil fails, disabling the ignition system. this seems to accord with the observed symptom of gas pedal cutting out and the car slowly dying, then not starting. whereas an air or fuel issue would presumably result in a harder cut-off of the engine.

does this seem vaguely reasonable and accurate?
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Old 09-08-2020, 01:36 PM   #17
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I spoke with an electronics friend of mine and he suggested that the out-of-spec resistance readings are problem so small as to be within the limit of Southwire meter's accuracy (which is, per the manual, 1.5% +/- 5 digits) and also so small as to not clearly indicate a fault with either part. he is a not a volvo guy but I trust his judgement.

anyway, I've not had any issues since last posting, but haven't gone on any 1hr+ trips. I ran a redundant ground off the alternator which has given me a stronger volt reading in the dash gauge, but I am not sure if that was ever the problem. I previously was running the original 35yr old wire ONLY, so it is possible that that wire was intermittently faulty - but I would've suspected that the car would have different symptoms than the ones I described if this were the case.

anyway, the case is still open. thanks for yalls help.
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Old 09-09-2020, 03:39 AM   #18
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I've had a very similar set of symptoms this summer in my 86 DL - car cutting out intermittently, would start back up fine. Over time it got more likely to die and had to sit for a minute or two before it would start again. It would usually cut out in roughly the same places on my route home from work, on a flat stretch a minute or two after going up a short steep hill, so I initially thought fuel delivery. Occasionally the tach would bounce around after it cut out, but mostly it would just drop to zero. I did some of the basic troubleshooting, checking ground points, fuses, relays, fuel pumps, etc. Took it to a Volvo mechanic and they came up with pretty much the same list of suspects as ZVOLV above.

My distributor is only a few years old and the other bits all seemed in good order so we decided to try replacing the ICU first. Got one from FCP (remanufactured by Programa) - was DOA. RMA'd it, second one worked, and my car felt better than it had in quite a while. For two glorious test drives. Then it started cutting out again. Same symptoms, but over the course of a week it went from dying once or twice in 30 minutes of driving round town to only running for about 30 seconds at a time and needing a couple minutes before starting again.

I did a lot more research (including this thread!), testing, cleaning, and general fiddling with electrical stuff in the fuel and ignition systems. Verified spark from coil wire to strut tower bolt. Replaced ignition harness with a new one from Dave Barton (replaced main harness years ago) - no change in symptoms. Went to the junkyard this weekend and grabbed a distributor from an 85 and ICU from an 88. Tried swapping the distributor first - ran great...for 30 seconds at a time. Plugged in the junkyard ICU - ran great, hasn't cut out once since, feels confident. The irony is the junkyard ICU has an old sticker on it saying it was remanufactured by Programa.
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Old 09-10-2020, 01:49 PM   #19
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thanks for your story and info, radar. I have wondered if it may be a dying ICU or even ECU. I partially suspect ECU in my case as my idle speed does NOT increase when I kick on the AC despite the inputs from the microswitch to the ECU operating normally. and since every input to the ECU is in spec yet I still have this issue.

thanks yall
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