mimino
Senior ZX2ner
Posts: 352
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Post by mimino on Sept 12, 2018 11:50:10 GMT -5
Looks like I will be the first one with an issue here lol
*I'm boosted, if that makes any difference.
Car developed a dying in neutral problem recently. Only happens when the car is hot (after a nice cruise on the highway) and only at higher speed, never just at idle. Let's say I'm coming off an off-ramp, clutch in and see the rpm drop past 1k and it just dies. Same thing if i were to drop it into neutral. My hunch it's iac related, but could also be something more serious, like a crank walk (i will be taking the crank shaft sensor out today). Could also be a boost/vac leak, but that's a distant third at the moment.
Any other suggestions? Good to have some sort of a forum back. Thanks, Evil!
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Post by davidgettle on Sept 12, 2018 13:45:35 GMT -5
The IAC is known to stick in these cars, especially when the engine is hot. But you know that. That is where I would start, they are cheap, and fairly easy to replace.
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mimino
Senior ZX2ner
Posts: 352
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Post by mimino on Sept 15, 2018 22:22:42 GMT -5
Did several things:
1. took the iac out and ohmed it out - around 10.x ohms on it, so it "appears" to be functional, but doesn't completely rule it out. 2. crank sensor is not chewed up, so hopefully no cw here 3. no boost/vac leaks after pressurizing the system 4. hooked up a fuel pressure gauge and getting 30 psi at idle. revving it up it goes up a few psi, but not much.
the problem seems to be more pronounced if the road is at a decline, which in my mind points to a fueling issue. i was wanting to upgrade the pump to a proper walbro, anyway.
Any thoughts?
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Post by TheEvilZX2 on Sept 16, 2018 17:14:58 GMT -5
i had a very similar problem many years ago and was surprised to find out my problem was one of the fuel pressure sender wires. by dumb luck i stumbled upon the internally broken wire by wiggling wires around and the car died in my driveway. i cut and soldered it then and there and didnt have any issues until i was boosted many years later.
are you able to datalog? if so datalog fuel pressure and go try and recreate the issue, if this is the case fuel pressure falls flat on its face when the car dies.
oh and ive actually had this issue with both theevilzx2 and my daily/beater. same wire very similar issues.
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mimino
Senior ZX2ner
Posts: 352
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Post by mimino on Sept 16, 2018 18:05:48 GMT -5
by sender you mean the fpr?
i went out and bought a new iac today. as soon as i installed it and cranked it on, the rpm quickly went up to 2k and slowly dropped to about 1k where they should be (how a healthy iac should behave). i don't recall the old iac doing this, as the rpm would quickly settle right around 1k from the startup. i go "that's looking promising" and took it out for a drive. several lights down, it stalls, i restart, it stalls again and finally throws a cel. i check it and it's p1504 (iac circuit malfunction). now, some moons ago i had to fuck with the iac plug for some reason and the wiring job was not the best. i wiggled the wires at the plug and it killed it, so now i'm ordering a new plug and hoping that will take care of this issue. i'm surprised the car won't even start with the iac unplugged, tho.
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Post by TheEvilZX2 on Sept 16, 2018 18:25:02 GMT -5
fuel pressure sender, its not technically a regulator interesting, ive never touched my IAC, stock 180k in there now, everything just got new gaskets before it got turboed. definitely fix the IAC wiring first and see if it keeps acting up
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mimino
Senior ZX2ner
Posts: 352
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Post by mimino on Sept 19, 2018 10:05:11 GMT -5
plug should come in Thursday. i've done some "special things" to the knock sensor plug to make it fit on the iac lol no more codes, but it's still stalling after the warm-up. i'm not ruling out the wiring just yet, until i properly replace the plug. however, i've logged some stats with my obd2 bluetooth reader and during the times that the rpm drop, the voltage reported by the adapter drops into 11.x V. The battery is 8 years old, so I've taken it to get tested this morning, and it's bad. It's charged up but not holding during the load test. It's a deferred maintenance at this point, but could that be in any way related?
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Post by davidgettle on Sept 19, 2018 12:12:42 GMT -5
Based on the way your car is acting, and the battery condition I would also have the alternator checked, the battery condition and a bad alternator could be a combined issue causing the power drop.
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mimino
Senior ZX2ner
Posts: 352
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Post by mimino on Sept 20, 2018 20:16:15 GMT -5
new plug and battery in - still dying. more pronounced on a downslope, if that makes any difference.
tested for boost leaks again and got nothing, other than my bpv (1g dsm) leaking a bit, but these are notorious for that.
i still don't like the fuel pressure readings (right around 30 psi at idle). i'll take the old pump out and inspect it. might even order that walbro finally, but feeling like I'm just throwing parts at it at this point.
disconnected the maf and drove around - same. disconnected fpr and that bumped the idle pressure to about 40 psi, and it felt like it took longer to start dying. still no codes.
any more ideas?
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Post by TheEvilZX2 on Sept 21, 2018 15:40:21 GMT -5
do you have the ability to datalog? it would be nice to see what the computer sees when the car dies
im still not convinced its not the fuel pressure sender wires. ive had two different zx2s do this exact same thing and it was the same wire on the fuel press sender...
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mimino
Senior ZX2ner
Posts: 352
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Post by mimino on Sept 21, 2018 18:55:23 GMT -5
just noticed i do have fuel pressure on my app i'm using. i will give it a try, hopefully tomorrow. when i wiggled those wires while the car was idling, there was no change.
i will also try and pull the pump tonight and see if anything looks off in the tank.
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Post by TheEvilZX2 on Sept 22, 2018 9:46:26 GMT -5
let us know.
this is quite odd if its not the fuel pressure sender. this was the only problem I've had to fix (refix i guess) since going turbo. if it something else causing this problem for you I definitely want to know!
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mimino
Senior ZX2ner
Posts: 352
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Post by mimino on Sept 22, 2018 15:15:42 GMT -5
so i pulled the old pump last night. didn't see any holes in the lines or anything, but decided to throw in a low mileage stock pump to test. drove around this morning and it hasn't died once, but the rpm would drop pretty low at a couple of test stops i made (going downhill and braking to a stop), but then rebound back to normal. the afr goes super rich during this low idle situation (makes sense, since there is far less air than fuel at such low rpm). the fuel pressure readings are not available in the torque app for this car (they're there but no readings). i'll go on a longer test drive and do more checks. funny enough, it runs pretty good with the stock pump and doesn't lean out under boost.
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Post by TheEvilZX2 on Sept 23, 2018 8:06:15 GMT -5
did all of this just start happening all of a sudden? why do your RPMs drop like that? has it always done that or is it new since the dying issue?
whens the last time your timing was done?
EDIT: a missed ignition event will cause a rich condition on a wideband, how is your ignition system?
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mimino
Senior ZX2ner
Posts: 352
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Post by mimino on Sept 23, 2018 13:47:12 GMT -5
yeah, it just started happening within the last month. first time i've noticed it died on an off-ramp (also slightly downhill) and it got progressively worse since. i'll check the plugs, not sure how old the wires are, but definitely not that old (maybe 10-20k). i do have a spare coil i can try, but it has no issues firing up. could a crankshaft sensor still be the cause? did some googling last night and some folks were having these intermittent stalls that went away with a new sensor.
let me know if you don't have excel, and i'll upload a csv one. I've conditionally highlighted the rpm values where they fall below 800 rpm.
I'll go out and dick around with it some more today.
Thanks!
Edit: threw in a different maf and noticed the front o2 wires were frayed, so i threw in an older working o2 i had. Went for a drive and it stalled again... captured it in this log (line 6667):
Edit #2: I wonder if this is realted at all. Late last year I've developed a no start from the first try that can be seen here:
It has since been starting just fine, but this reminded me of how it would act when iac is unplugged. fire and die right away. hmm.
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mimino
Senior ZX2ner
Posts: 352
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Post by mimino on Sept 24, 2018 15:22:03 GMT -5
I pulled plugs and they were good then started pulling wires. Cyl 1 & 2 had much weaker spark. First I tried a different coil I had and same result. Got new wires and 1 & 2 are still sparking much weaker than 3 & 4. See vids below: ufile.io/ob6chufile.io/q3odyMy bpv is leaking under boost and at idle as well. Not much, but I'm wondering if that could contribute to anything, even if it's a recirc bpv. Shit, I also wonder if this iac i got is bad... might go and exchange it for shits and giggles. This is driving me nuts lol
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mimino
Senior ZX2ner
Posts: 352
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Post by mimino on Sept 24, 2018 21:09:34 GMT -5
just posted on the fb page:
" fuck me sideways... found a leak that wasn't there before, I swear lol During this boost leak test it actually whistled quite violently.
One of the hoses running to the booster from the im. I've also gone ahead and turned in the "new" iac I got over the weekend. It looked bootleg af (scratched, double yellow stickers on the box -Advance Auto), and the "new new" one I got actually looked legit. Popped it in, fixed the leak and started car. Idled beautifully and actually a bit higher than "normal" of what I've gotten used to. Gave her a test drive and it ripped. Feels like it's pulling a lot stronger too (nice temps tonight). Never stalled once and the rpm didn't dip at all. Clutching it brings the rpm up above 1k, then settles down to hot idle. Tried multiple quick stops and no issues.
Knocking on the wood here. Don't ever underestimate vacuum leaks..."
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Post by TheEvilZX2 on Sept 25, 2018 15:09:45 GMT -5
quite the wild goose chase. glad you potentially found the problem, lets hope this fixed it for good!
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drew
Early Adopters
Posts: 195
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Post by drew on Sept 25, 2018 19:46:12 GMT -5
Hurra!!!
Sent from my SM-S727VL using Tapatalk
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mimino
Senior ZX2ner
Posts: 352
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Post by mimino on Sept 26, 2018 9:12:01 GMT -5
a bit of a twist lol took it on a highway run last night and it never died, but a cel popped up. sometimes i get a rich code after disconnecting the battery and doing short pulls, so i didn't think much of it. well, it gave me a p1506 - iac overspeed. i can tell the idle, after blipping the throttle, isn't returning as fast back to normal - which doesn't bother me much, since driveability is good. i boost leaked it again and got nothing, so off i go ordering yet another iac. i think the ones from advance are straight up garbage... i'll keep you guys updated.
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Post by TheEvilZX2 on Sept 26, 2018 15:36:10 GMT -5
screw advance auto, check HEREdont forget we've got a discount code too!
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mimino
Senior ZX2ner
Posts: 352
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Post by mimino on Sept 26, 2018 19:36:47 GMT -5
screw advance auto, check HEREdont forget we've got a discount code too! yup. got me one from there. should be in by fri/sat.
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mimino
Senior ZX2ner
Posts: 352
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Post by mimino on Sept 28, 2018 16:25:40 GMT -5
new iac is in. doesn't hang the rpm anynmore, so looks like 2x iacs from advance were garbage... took it out for a spin and it didn't stall, but the rpom do drop low (about 500 or so), but then rebound back up to 900 every now and then. thinking about driving to a shop that can run iac tests on it (command the increase/decrease in airflow from the scanner) to see what's going on. just glad it's not dying anymore lol
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mimino
Senior ZX2ner
Posts: 352
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Post by mimino on Oct 6, 2018 18:43:36 GMT -5
Alright. Not sure if this the resolution, but it hasn't died the few times I've tested it since. Took it to my mech today and we started hooking it up to his obd2 fancy shmancy scanner and soon as he'd plug it in, the car started idling weird and threw a tps (p0122) code. Odd. Tested tps and everything passed. Looked at a couple of other things and everything checked out. He goes: "Do you have a chip on this thing for your tune? Chips are known to mess with stuff, as the mask/fool the comp readings" Of course I do... lol my tune is burned onto a piggyback that's plugged into the pcm. Took that out, cleaned the contacts and put it back in. Don't ask me how, but it hasn't died *yet* (knock on wood).
Need to start thinking about getting it dyno tuned, as the chip came from a car that was probably full of boost leaks and other crap. Runs way too rich (probably tried compensating for leaks with more fuel) for my liking. Too bad it's going to cost at least $500-700. Evil, want to make some money? lol
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Post by TheEvilZX2 on Oct 7, 2018 8:06:55 GMT -5
youre running a piggyback? like an actual chip on the computer? youre not running a 98 computer are you?
I'm down to help tune it, but I always heard there was problems tuning the 98 computers, just want to make sure youre not running one....
Do you have SCT PRP? im down to help you get it tuned up
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mimino
Senior ZX2ner
Posts: 352
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Post by mimino on Oct 7, 2018 15:37:59 GMT -5
yup, it's a 4-wire MTA4 pcm. I do recall hearing about issues with 98s also. Do you have anything saved on what that was all about?
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Post by TheEvilZX2 on Oct 7, 2018 16:11:20 GMT -5
shit
honestly i dont remember what specifically it was about them just the programming in general on those earlier pcms...
i would strongly encourage swapping to a 99.5+ pcm, and getting an SCT X4 (or X3) and SCT PRP. I'd be able to start helping you from there
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Post by TheEvilZX2 on Oct 7, 2018 16:12:26 GMT -5
or....megasquirt.....
mine is built, im just not running it yet. can still help with that too
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mimino
Senior ZX2ner
Posts: 352
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Post by mimino on Oct 11, 2018 9:10:00 GMT -5
lol i actually went from a 99.5+ down to 98 just for this chip... one of the local tuner shops offered the megasquirt option as well. what's the most complicated part of that? i'm not a total dum-dum, but never done anything remotely close to this.
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Post by TheEvilZX2 on Oct 11, 2018 16:50:40 GMT -5
well shit
as for megasquirt, i guess it depends on your capabilities really. some people cant/dont want to solder and will pay more for a preassembled kit. from there, simply put its wire up and tune.
but in reality its RTFM, a lot...seriously. the manuals have so much information in them its intimidating at first and can be hard to find things because its not specific to any one vehicle. you need to know what kinds of sensors and trigger wheels you're running your engine on and so on and so forth.
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