14 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHbackfire/misfire (big boom!)
Leading reported evidence
Check no intermix either way
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Leading evidence: 'Check no intermix either way' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check any fire damage (it was a really big boom)' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed · Original poster
Shut down, inspected the throttle cable, with no defects noted.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed · Original poster
Pulled the MAF (carefully) and inspected with no damage noted.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
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0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
14 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261027T075545Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Cranking motor after a five minute cooloff after a 120 mile drive. Nothing out of the ordinary noted.
Engine cranked over normally about 3 revolutions (or so), when BOOM!! and a big cloud of bluish smoke came out of the rear of the car.
Thinking that there was pissibly an induction fire (a la airplane piston engines), I continued to crank for a period of time to put out the possible fire. Very strong misfire, with minor pops for appx 1 minute.
Let the motor cool for 2 hours, pulled the air filter. No damage (lots of leaves though). No oil behind the butterfly noted. Pulled the MAF (carefully) and inspected with no damage noted. Reassembled everything and tried to start the motor with the MAF disconnected. Durametric codes of P1602 and P0102 pulled and cleared. Disconnected the battery for 30 minutes.
Instantly tried to go full throttle. Probably got up to 5000 rpm before I could react.
Shut down, inspected the throttle cable, with no defects noted.
Reconnected the MAF connector. Tried another start. Serious misfire, minor backfiring. Will not accelerate much beyond 1000 rpms.
No further codes came up, no indications from the Durametric-which I had to uninstall, reinstall and install another Windows driver.
BTW I borescoped around the intake runners, and didn't see anything unusual.
Any ideas?
Fuel delivery seems ok, based upon the rapid rise in rpms with the MAF disconnected. Don't understand why that happened, though.
Background: 16k miles after overhaul. No detritus noted when I removed the oil pan for a repair last week.
Normal cranking/operation since overhaul.
New AOS, Oil filler cap seal/tube all filters, etc.
More than half full of fresh fuel.
Let's go over this and maybe it will prompt smarter people than me to rescue us?
1. Lots of heat soak during the 5 minute 'cool-down'. Cats will be very hot.
2. Suppose you have a leaking injector, when you start it will blow raw fule straight into a very hot cat. Boom !
3.Durametric confirms it is not a timing problem. So it must be overfueling.
4.If it makes you feel better about replacing them, there are upgraded injectors available.
Good to hear there's no intermix. Did you go to DME/Actual values and click on the misfire counters for each individual cylinder? These counters are updated in real-time so the engine will need to be running.
Were the coils and spark plugs replaced during the rebuild?
Yes, i replaced just about everything. I tried to get to the individual values, but there was some issues with my laptop/Durametric, I guess. I'll try again tomorrow.
Also try disabling each injector (using durametric under dme/activation) and see if it makes any difference. That may help isolating a bad cylinder. Was the idle control valve cleaned? Cam deviation values?
Still can't explain your big boom though.
After disassembly I discovered the following:
Throttle body displaced to the left, causing a large vacuum leak
Connector tube also displaced to the left, connection hose ruptured in two places
intake manifold gasket displaced on #1 cylinder
I still need to pressure test the intake manifold on the left side to ensure there are no cracks, etc. even though none are visible.
I believe that the #1 injector was leaking, such that it allowed a quantity of gas to accumulate in the head above the intake valve. When I tried to start it, it flashed over and BOOM!
Replacement gaskets, connector tube, injectors and BTW a new battery cable, since mine is corroded. Cranked ok though. (Maybe a new seat bottom if I can't clean the origional seat up)
Anything I might be missing?
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