Stumped

satanburns1 · 08-20-2012, 07:22 PM

So i been chasing this on and off problem.

Car is a 92 940 Turbo. No DTC stored. starts runs drives. Every once in a while ( regardless of boost level, gear, or % throttle) itll get to 3000 RPM and backfire a few times. If i get off on first backfire itll rev out...but it'll also rev if i just stay in it.

I have swapped fuel ECM spark ECM, distributor, cap rotor wires ( coil wire also) RPM knock sensor, ETC sensor, TPS, FP relay, RS realy, coil, MAF, resistor pack, power stage and its the same every time( im sure there were other parts i swapped also but always the same) Only thing i tested and came up out of spec was primary side of coil. got 3 ohms. Tried several coils and they all ohm above 1 ohm. lowest was 1.4 highest was 3 ohms. Now i wanted to stay OEM as hell but i was reading and it seems the MSD or ACCEL coil is damn close resistance wise at least. What do you guys get when you ohm the two terminals w/o the terminals attached? Secondary was 7k-10K on all of them. Am i wrong in thinking that higher resistance means it takes more power to induce the needed voltage?

I work at a dealer so alll parts are from running cars or right out of the box.

Fuel presssure is 2.5 bar running 3.0 bar w/o regulator vac hose on. O2 sensor re- acts properly ( but i have a new one to slide in there) Its not fuel cut cuz it happens @ any MAF voltage.

The fuel pump is from a 2006 S60. I took the sender apart and swapped it into it. The pump was also from a running car and was replaced for a leaking sender. It has a check valve built in. Removed under car pump months ago. I smell fuel when it happens and it i play with throttle i can load up exhaust enough to bark some nasty flames. The amount of fuel leads me to believe its spark related.

Im trying to get this to stage 0 before i turn the 5th injector back on and turn the boost back up. Stage 0 does include a new engine. I was thinking that mine has gotten so loud that it was retarding the hell out of my timing. I moved the knock sensor to the intake and then left it hanging. same.

So i ask.. Ideas? Experiences? Something i havent checked?

satanburns1 · 08-20-2012, 08:27 PM

I dont want to drop a fresh motor in and hurt it by having a problem. I wont know until I do tho at this stage. Im gonna backprobe KS tomorrow. Maybe compression test as well cuz it is a noisey sob.

satanburns1 · 08-22-2012, 06:24 PM

anyone? cant find any harness faults and still no DTC set other than speedo signal missing.

Mueller · 08-22-2012, 06:33 PM

did you do the compression test? how about a leak down test?

satanburns1 · 08-22-2012, 08:19 PM

Not yet. I know my bores are loose. Like very loose. Im scared to ha ha. My BMW squirters arrived today. Stage 0 block is next regardless. I had the head off about 100k ago. Could move #1 cyls a good amount.

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08-20-2012, 07:22 PM	#1
satanburns1 @ stage -5 currently Join Date: Feb 2012 Location: Brick NJ.. Yeah BRICK	Stumped So i been chasing this on and off problem. Car is a 92 940 Turbo. No DTC stored. starts runs drives. Every once in a while ( regardless of boost level, gear, or % throttle) itll get to 3000 RPM and backfire a few times. If i get off on first backfire itll rev out...but it'll also rev if i just stay in it. I have swapped fuel ECM spark ECM, distributor, cap rotor wires ( coil wire also) RPM knock sensor, ETC sensor, TPS, FP relay, RS realy, coil, MAF, resistor pack, power stage and its the same every time( im sure there were other parts i swapped also but always the same) Only thing i tested and came up out of spec was primary side of coil. got 3 ohms. Tried several coils and they all ohm above 1 ohm. lowest was 1.4 highest was 3 ohms. Now i wanted to stay OEM as hell but i was reading and it seems the MSD or ACCEL coil is damn close resistance wise at least. What do you guys get when you ohm the two terminals w/o the terminals attached? Secondary was 7k-10K on all of them. Am i wrong in thinking that higher resistance means it takes more power to induce the needed voltage? I work at a dealer so alll parts are from running cars or right out of the box. Fuel presssure is 2.5 bar running 3.0 bar w/o regulator vac hose on. O2 sensor re- acts properly ( but i have a new one to slide in there) Its not fuel cut cuz it happens @ any MAF voltage. The fuel pump is from a 2006 S60. I took the sender apart and swapped it into it. The pump was also from a running car and was replaced for a leaking sender. It has a check valve built in. Removed under car pump months ago. I smell fuel when it happens and it i play with throttle i can load up exhaust enough to bark some nasty flames. The amount of fuel leads me to believe its spark related. Im trying to get this to stage 0 before i turn the 5th injector back on and turn the boost back up. Stage 0 does include a new engine. I was thinking that mine has gotten so loud that it was retarding the hell out of my timing. I moved the knock sensor to the intake and then left it hanging. same. So i ask.. Ideas? Experiences? Something i havent checked?

08-20-2012, 08:27 PM	#2
satanburns1 @ stage -5 currently Join Date: Feb 2012 Location: Brick NJ.. Yeah BRICK	I dont want to drop a fresh motor in and hurt it by having a problem. I wont know until I do tho at this stage. Im gonna backprobe KS tomorrow. Maybe compression test as well cuz it is a noisey sob.

08-22-2012, 06:24 PM	#3
satanburns1 @ stage -5 currently Join Date: Feb 2012 Location: Brick NJ.. Yeah BRICK	anyone? cant find any harness faults and still no DTC set other than speedo signal missing.

08-22-2012, 08:19 PM	#5
satanburns1 @ stage -5 currently Join Date: Feb 2012 Location: Brick NJ.. Yeah BRICK	Not yet. I know my bores are loose. Like very loose. Im scared to ha ha. My BMW squirters arrived today. Stage 0 block is next regardless. I had the head off about 100k ago. Could move #1 cyls a good amount.