home register FAQ memberlist calendar

Go Back   Turbobricks Forums > Mechanical > maintenance & nonperformance

Reply
 
Thread Tools Display Modes
Old 05-02-2019, 08:05 PM   #1
Mbeas96
Board Member
 
Mbeas96's Avatar
 
Join Date: Aug 2017
Location: Charleston
Default 740 possible spark problem?

1990 740 lh2.4, aw71, chipped ezk and wasted spark using miata powerstage and bosch coil pack (out of a land rover discovery), recently non chipped 9xx fuel ecu which fixed my random rich stumble/misfire, 16t at 12psi, npr intercooler, t5 injectors and resistor pack bypass, do88 turbo inlet hose

On my 25 mile trip home from work, all was fine, passed a couple people on the 2 lane highway and not a hiccup. All the way until about 2 miles away form my house, i floor it from a stop and it is taking off alot slower than usual building boost and as soon as it hits 10psi it starts bucking and misfired right before i let off. Very suprised i let it cool for about a mile and a half and tried to slowly build boost in a higher gear. It is very inconsistent power and bucks alot. AFR's on the guage show it goes from 12s to 14s and back again.

Thinking i was experiencing some sort of spark blowout, I made it home, let it cool, and reseated the plug wires on the plugs and onto the coil pack. Also made sure there were no tears in the wires. This time, pulling out the driveway switching from reverse to nuetral the afrs went full lean (17+) and the rpm guage was barely above 0, car was shaking and about to turn off, i tapped the gas and the problem stopped. idle normal and made it to the end of my road. Went to turn onto the highway and same thing. Shaky car, lean reading and dying rpms.

Let off the gas and got bakc on it and it pulled out into traffic fine. But as soon as i tried to get into boost, afr's start going crazy, bucking and farting start. Went half a mile to a gas station, turned it off, started fine, idled fine, pulled thru the parking lot fine, but again more than like a quarter throttle and things start to go wrong.

No CEL, no codes on sockets 2 or 6. rsr and harness and fuel pump relay replaced around 6 months ago, plugs and wires around a year old. Not to sure where i should start checking things out. Usually when things go wrong with this car it pops a cel code or something to get me started...
__________________
Quote:
Originally Posted by Mr.Bill View Post
You are not a man unless you've thrown up at a turbobricks meet.

My build thread: http://forums.turbobricks.com/showthread.php?t=340910
Mbeas96 is offline   Reply With Quote
Old 05-02-2019, 08:26 PM   #2
2turbotoys
Salaminizer
 
2turbotoys's Avatar
 
Join Date: Nov 2007
Location: Reading pa
Default

I would start with easy stuff...remove and examine all intercooler piping, or pressure test it, I had a similar problem, checked all the tubing, and swore up and down there was no leaks...turns out I did, output of intercooler, on the bottom of the hose. The only way I found it was a tiny bit of oil had started to come out an it got on my hand.

I'm sure you thought of leaks, but look super carefully at every one.
__________________
Feedback thread https://forums.tbforums.com/showthread.php?t=144924

1979 242 B21 on MS, waiting on L33
2006 V50 T5 AWD 16 PSI +
2turbotoys is offline   Reply With Quote
Old 05-02-2019, 08:45 PM   #3
Mbeas96
Board Member
 
Mbeas96's Avatar
 
Join Date: Aug 2017
Location: Charleston
Default

In all honesty...rather than a glance around I didn't check for leaks. If it is a tear, I have a suspect in mind...I'll look more into it tomorrow, if none found I'll set up the pressure tester and see what happens.
Mbeas96 is offline   Reply With Quote
Old 05-02-2019, 08:51 PM   #4
2turbotoys
Salaminizer
 
2turbotoys's Avatar
 
Join Date: Nov 2007
Location: Reading pa
Default

Good luck! I hope it's that easy, but it sounds very likely to me
2turbotoys is offline   Reply With Quote
Old 05-03-2019, 05:45 PM   #5
Mbeas96
Board Member
 
Mbeas96's Avatar
 
Join Date: Aug 2017
Location: Charleston
Default

Pressure tested today after work and sprayed soapy water everywhere. I found a small leak, also by the output of the intercooler. Got that pretty much squared away. The problem has also seem to have gotten worse? over the last 24 hours. Originally i could drive, just not hit the gas very hard or things would start going bad. Now, i start the car and it's not driveable. It's shuttering, idling low and running lean. It will not rev, if you hold your foot on the gas it'll slowly rise but sounds like it's being choked or something.

I tried unplugging the AMM and the engine shut off, so that seems to be working. I'm tempted to swap coil packs to my spare, or swap ecu's back to the 5xx

Here is a little clip of earlier after the pressure test...


Last edited by Mbeas96; 05-03-2019 at 05:50 PM..
Mbeas96 is offline   Reply With Quote
Old 05-03-2019, 07:51 PM   #6
bobxyz
Board Member
 
bobxyz's Avatar
 
Join Date: Aug 2014
Location: Boulder, Colorado
Default

Will it idle without assistance? If so, try wiggling all the wires that you can get to. It sounds like a bad connection, or a short, especially since it seemed to show up with vibration.
bobxyz is offline   Reply With Quote
Old 05-03-2019, 08:08 PM   #7
2turbotoys
Salaminizer
 
2turbotoys's Avatar
 
Join Date: Nov 2007
Location: Reading pa
Default

Do you have a spare AMM?
2turbotoys is offline   Reply With Quote
Old 05-03-2019, 08:16 PM   #8
Mbeas96
Board Member
 
Mbeas96's Avatar
 
Join Date: Aug 2017
Location: Charleston
Default

It'll idle, at about 200-300 rpm. I'll go wiggle everything in sight. Will report back

And not currently, my last one failed...

I'll break out the multimeter and see if I can test it

Last edited by Mbeas96; 05-03-2019 at 09:21 PM..
Mbeas96 is offline   Reply With Quote
Old 05-04-2019, 12:48 PM   #9
Mbeas96
Board Member
 
Mbeas96's Avatar
 
Join Date: Aug 2017
Location: Charleston
Default

Did the jiggle test on the spark plug wires, coil pack wires, everything associated with the wasted spark that's in the engine bay, and the rsr since I wired that in too. Nothing changes...

Pulled the spark plugs, a little oily from my leaky cam cover and number 3 is a little dark...but I don't think these would be my culprit. The wires are only a year old and seem like the sheath is still in great condition. They were however all gapped to around .42 so I put them back down to .29-.30 and reinstalled. No change in the cars symptoms.

Can't find the multimeter atm...so no info on that right now

The car sounds different. Like more throaty or something..maybe cause it's just running bad but could a clogged cat be causing this nonsense? It's the original I assume.

Also checked the fuel pressure. Engine off key on pressure is 38lbs. Engine idling pressure is 38-40. Trying to rev, probably only getting to 1200 or so and it's going from 35-40. No gas in the fpr line.

Edit. Just swapped in the 560 ecu and no change. Coil pack will be next when I can find it..

Last edited by Mbeas96; 05-04-2019 at 01:07 PM..
Mbeas96 is offline   Reply With Quote
Old 05-05-2019, 08:58 AM   #10
Mbeas96
Board Member
 
Mbeas96's Avatar
 
Join Date: Aug 2017
Location: Charleston
Default

My brother gave me another spare AMM to try.

Plus we were talking about spark plug 3 that was dark compared to the others. Maybe that cylinder is being flooded with fuel? So today I'll take off the fuel rail and see about rigging something up to test the spray patterns of the t5 injectors. Hopefully when needed I have one extra from when I bought the set I could throw in.

Also for some cheap insurance I'll grab a new set of copper ngks and gap them down to around .022 instead of .03.

I wish I knew whether it is spark or fuel related. Anybody know how to figure that out? :D
Mbeas96 is offline   Reply With Quote
Old 05-05-2019, 10:10 AM   #11
Mbeas96
Board Member
 
Mbeas96's Avatar
 
Join Date: Aug 2017
Location: Charleston
Default

Backfiring out the intake when trying to start? Never heard that before...

Swapped AMM and coil pack. Didn't do it. The car seems to have gotten worse. Won't stay running anymore. Won't fire on the first try. It will eventually after a few cranks but idles so low that it eventually shuts off.

The car has like an 1/8th of a tank right now. Is it possible the intake pump is shot and it's running like this because the gas is to low for the main pump? I opened the access panel and it looks like the original, pretty crusty. But it primes with the key...Idk

Still no codes from the box
Just thought about it...it's probably running worse when it's cold, then I've also reset the computers. So maybe it's still the same when it's warm. Just can't get it warmed up because it won't stay running.

Swapped FP relay to new one I had. No changesssss

Last edited by Mbeas96; 05-05-2019 at 10:30 AM..
Mbeas96 is offline   Reply With Quote
Old 05-05-2019, 01:49 PM   #12
mocambique-amazone
Board Member
 
Join Date: Jul 2012
Location: Germany
Default

If your in tank pump is dead and the fuel level is less than 1/4 the main (and now only) pump ttry to suck the fuel heavy. This will produce under pressure. The fuel will start to bubble/foam. A injected engine won't run with fuel-foam. Result: to lean (backfire to the inlet side)
The ECU wants to compensate, no chance.

First to check: in tank pump.
Maybe your car is with the schrader-valve in front of the main pump. Otherwise open the fuel line between the in tank and the main pump.
If the in tank pump is dead/clocked fill up the fuel cell.
Or swap the in tank pump first.
Maybe a wallbro in tank as a main pump will be your solution.
Good luck, Kay
mocambique-amazone is offline   Reply With Quote
Old 05-05-2019, 08:53 PM   #13
Mbeas96
Board Member
 
Mbeas96's Avatar
 
Join Date: Aug 2017
Location: Charleston
Default

The intake pump definitely primes with the key. Not positive that it's on while running. But my thought were maybe a hose on the inside of the tank is torn or something like that?

Either way, I put around 2 gallons in and still the car wont start...not sure why it has progressively gotten worse. More gas?

I guess starter fluid next? I want to see the injectors spray pattern but the fluid will probably happen tomorrow.
Mbeas96 is offline   Reply With Quote
Old 05-06-2019, 07:29 PM   #14
Mbeas96
Board Member
 
Mbeas96's Avatar
 
Join Date: Aug 2017
Location: Charleston
Default

Okay so, put original coil pack back on since I didn't yesterday and still no start. It was trying to fire but wouldn't stay running. Thinking back to my thought of injector 3 being stuck open, I unplugged it and nothing changed. So I sprayed some starter fluid directly into the intake and nada. Didn't even try to fire.

Took the plugs out and all of them are soaked with gas. I have new ones but I broke a plug wire pulling it off...I'll track some down tomorrow hopefully.

How do you test spark with a coil pack? Either they aren't firing or the injectors are just unloading the fuel...
Mbeas96 is offline   Reply With Quote
Old 05-06-2019, 09:27 PM   #15
2turbotoys
Salaminizer
 
2turbotoys's Avatar
 
Join Date: Nov 2007
Location: Reading pa
Default

Test the same way as you would without coil packs? lay plug on something steel on the motor and see if it sparks? I have never tried it with coil packs, seems like the question is why wouldn't they be working? I don't have experience with your setup, the only time I had coil pack problems was with my V50T5 and replacing them just fixed it.
2turbotoys is offline   Reply With Quote
Old 05-06-2019, 09:45 PM   #16
Mbeas96
Board Member
 
Mbeas96's Avatar
 
Join Date: Aug 2017
Location: Charleston
Default

Okay, makes sense lol. Never had to do it before so just making sure.

And no idea...taking stabs at the dark currently. Plus the igniter came from a 90's miata in a junkyard...Really I'm pinning things that I have personally messed with, even though everything is soldered, heatshrinked and zip tied in place.

Grabbed some plug wires from my brothers car while his sits, I'll throw the new plugs in tomorrow and see if they get coated with fuel. If so, connectors off injectors and see if the plugs still get coated. Rail off to check injector spray is my last idea.
Mbeas96 is offline   Reply With Quote
Old 05-07-2019, 08:25 PM   #17
Mbeas96
Board Member
 
Mbeas96's Avatar
 
Join Date: Aug 2017
Location: Charleston
Default

Gapped the new plugs to .26 and car started. Ran like dog ****. But started. Same symptoms as before, very low shaky idle. Barely runs and chokes more with throttle. Pulled the plugs and they are wet and reek of gas. About 10 seconds of cranking and 10-15 of running.

Let them dry and they didn't stink, put thme in and unplug the injectors and crank. They smell faintly of gas again.. it's gotten dark and I'll wait till tomorrow to pull the rail.

Either gas was still in the cylinders after about 30 minutes or they are leaking. I hope they are leaking
Mbeas96 is offline   Reply With Quote
Old 05-08-2019, 06:59 PM   #18
Mbeas96
Board Member
 
Mbeas96's Avatar
 
Join Date: Aug 2017
Location: Charleston
Default

https://youtu.be/k3o8gIU8-o4

Took the rail off..problem is Idk what I'm looking for. Besides them just pouring out gas. They definitely have a pulse. Watch in 480 if you can, you can actually see it

I feel like it looks how it should. They are pulsing, no one sprays significantly more than another. Maybe it is a spark issue

Last edited by Mbeas96; 05-08-2019 at 08:25 PM..
Mbeas96 is offline   Reply With Quote
Old 05-09-2019, 06:56 AM   #19
DET17
Reformed SAABaholic
 
Join Date: Nov 2009
Location: NW Georgia
Default

Quote:
Originally Posted by mocambique-amazone View Post
If your in tank pump is dead and the fuel level is less than 1/4 the main (and now only) pump ttry to suck the fuel heavy. This will produce under pressure. The fuel will start to bubble/foam. A injected engine won't run with fuel-foam. Result: to lean (backfire to the inlet side)
The ECU wants to compensate, no chance.

First to check: in tank pump.
Maybe your car is with the schrader-valve in front of the main pump. Otherwise open the fuel line between the in tank and the main pump.
If the in tank pump is dead/clocked fill up the fuel cell.
Or swap the in tank pump first.
Maybe a wallbro in tank as a main pump will be your solution.
Good luck, Kay
Good advice from Kay!

That intank pump is essential to feed the chassis pump, critical at low petrol level in the tank.

Before overhauling your ignition system, can you go back to a timing light and see if can see proper timing for the #1 spark? I've had some luck depending upon the engine when cranking, but proper timing of the spark is probably more important that "spark quality" itself.

Edit - is this vehicle still LH2.4?
__________________
Project "cheap thrills" build thread: http://forums.turbobricks.com/showth...67#post4211467

Feedback thread: http://forums.turbobricks.com/showthread.php?t=198746
DET17 is offline   Reply With Quote
Old 05-09-2019, 09:01 AM   #20
Mbeas96
Board Member
 
Mbeas96's Avatar
 
Join Date: Aug 2017
Location: Charleston
Default

It is still lh2.4. Which sets the timing itself, correct?

I realize this thread is getting long and alot of people don't read thru everything so here's a recap of whats happened so far...

740 lh2.4 specs in first post
Very low shaky idle, dies with throttle, was not this bad when it first occurred during WOT pull driving home from work.

Pressure tested system- checks okay
Checked fuel pressure - 38-40lbs
Fpr is not leaking out of vacuum line
Changed plugs
gapped new Plugs to .26
Changed a couple questionable plug wires
Swapped coil pack to spare that was working a few months ago...
Unplugged AMM car died, swapped AMM and no change in symptoms
Intake and in line fuel pumps prime with key
Changed fuel pump relay
Disconnected cleaned and reconnected rsr
Finally pulled rail last night and all injectors pulse fuel and look okay. Plugs still smell like gas after a few cranks
Mbeas96 is offline   Reply With Quote
Old 05-09-2019, 12:24 PM   #21
DET17
Reformed SAABaholic
 
Join Date: Nov 2009
Location: NW Georgia
Default

Have you pulled the LH error codes under hood? Lots of info there with online docs to guide you once you know what LH knows. Does the car rev up and just sound OK at 2K rpm? Or won’t idle and won’t make any rpm?
DET17 is offline   Reply With Quote
Old 05-09-2019, 12:32 PM   #22
Mbeas96
Board Member
 
Mbeas96's Avatar
 
Join Date: Aug 2017
Location: Charleston
Default

Sorry, forgot to put that in the last post with the recap. No codes on sockets 2 or 6. Both read 1-1-1.

It will idle, at around 2-300 rpm. And it will rev in park or neutral but it feels and sounds like it is being choked. You have to really give it throttle and hold it for a second for the engine speed to start rising.

After a while of running or cranking the plugs get to wet with gas and the car wont fire.
Mbeas96 is offline   Reply With Quote
Old 05-09-2019, 01:26 PM   #23
dl242gt
300+hp on the shelf club
 
dl242gt's Avatar
 
Join Date: Jun 2002
Location: S NJ, a suburb of Phila.
Default

I didn't see that you have checked the timing belt and that the cam and crankshaft are in proper timing alignment? Just one tooth off and it can run like you describe.

Also if you are LH2.4 then you have a 3 bar fuel pressure regulator. The pressure should be more like 45psi or so.

Put a spark plug in the end of the plug wire and ground the body of the plug to a good ground and observe the spark. If there isn't any or it's weak. You'll need to move back in the system. You can check the ignitor signal by back probing connectors with a meter to see if you are getting the pulses there. Just like an injector. How is the crankshaft speed sensor?
dl242gt is offline   Reply With Quote
Old 05-09-2019, 01:43 PM   #24
Mbeas96
Board Member
 
Mbeas96's Avatar
 
Join Date: Aug 2017
Location: Charleston
Default

I haven't cheked cam timing or anything since it was running and driving perfectly fine until the last 2 miles of my 30 mile trip. Belt is tight and I don't think it would have slipped. I'll definitely have a look tonight though...can't hurt to check

It does seem the fpr is a little low. I have the original 3bar at home that came off with the old fuel rail way back when. I'll throw that on there and measure it.

I'll definitely check the spark tonight.

Crankshaft speed sensor; I pulled off a junkyard car because it looked to be in almost perfect condition. I'll pull it to make sure the magnet is clean, the sheath is intact and looks good.

Ya know...timing would very well explain everything. Let's hope it's a few teeth off.

Last edited by Mbeas96; 05-09-2019 at 09:09 PM..
Mbeas96 is offline   Reply With Quote
Old 05-10-2019, 06:50 AM   #25
DET17
Reformed SAABaholic
 
Join Date: Nov 2009
Location: NW Georgia
Default

Also, do you still run the IAC? I learned the hard way..... when the TPS connector plug disassembles (inside the rubber boot) and your ECU does not see the TPS closed input, the IAC does not run. I cheated my car into running for years with the throttle stop screw. HOWEVER, the PWM IAC valve will set your idle perfectly, but it must see the input "closed" switch from the TPS.
DET17 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


All times are GMT -4. The time now is 06:00 AM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.