Signs of engine failure/detonation
12-28-16, 08:02 PM
#1
Signs of engine failure/detonation
Lets begin with a little background history. I have a 86 GXL with a s4 TII swap. Mods include:
FMIC, emissions delete, rtek 1.7 (more on this later), HKS honeycomb filter, E-fan, dual alt pulley.
So lets begin, i got this car while the original owner was in the process of swapping the drivetrain from an 88 TII donor car, he couldn't finish it so i offered to take it off his hands. Well after lots of work i was able to get the car to idle. The previous owner supplied me with 4 550cc injectors when i bought the car. I figured what the hell lets just use these since they are free, well maybe that was mistake number 1. After going thru the cooling system i filled it up with coolant and fired it up to allow it to come to operating temp and to bleed out any air that may have been trapped in doing so, after a few mins i took it for a test drive, Keep in mind i am not running any type of wide band or 02 sensor at this point. Reason being the PO had a wide band gauge installed previously, and he ended up keeping the sensor. I cannot find what wire on the main harness to install the oem one because the harness is cut and tapped like crazy. Moving on to the test drive: I slowly drove it out of the neighborhood and came out onto a main road close to home. The car seemed to run fine at this point, no stalling or anything, i then get it up to speed and i could feel hesitation. I thought maybe if i gave it some throttle then it would clear up, i get to about 3rd gear (about 30-40 mph) and I could hear a popping sound but not like a back fire. Kinda like popcorn but very faint, i get to a stop sign and the cars dies, I attempt to start with no avail, the car would start and idle but only for a second, the only way to keep an idle was to hold down the throttle. So i babied it back home (approx 1 mile). I pull it into the garage and the first thing i check was the wiring harness to the ECU. After peeling back the carpet i discovered i have an N333 ECU with the rtek 1.7. I went to pocketlogger.com and after reading what they posted about running 550cc injectors that engine damag could result, i really hope not.
I guess my question is do you guys think ill be ok once i replace the 2 550cc secondaries to 750cc? Or do you guys think i fucked it up by only driving a mile maybe even less? Are there any quick tests i can do to check the health of the engine? I pulled the lower spark plugs and they were brand new when installed, they were damp, not wet and had mild carbon build up that easily wiped clean. I dont have a rotary compression tester and im hesitant to use a piston engine compression tester. Any help would be greatly appreciated.
FMIC, emissions delete, rtek 1.7 (more on this later), HKS honeycomb filter, E-fan, dual alt pulley.
So lets begin, i got this car while the original owner was in the process of swapping the drivetrain from an 88 TII donor car, he couldn't finish it so i offered to take it off his hands. Well after lots of work i was able to get the car to idle. The previous owner supplied me with 4 550cc injectors when i bought the car. I figured what the hell lets just use these since they are free, well maybe that was mistake number 1. After going thru the cooling system i filled it up with coolant and fired it up to allow it to come to operating temp and to bleed out any air that may have been trapped in doing so, after a few mins i took it for a test drive, Keep in mind i am not running any type of wide band or 02 sensor at this point. Reason being the PO had a wide band gauge installed previously, and he ended up keeping the sensor. I cannot find what wire on the main harness to install the oem one because the harness is cut and tapped like crazy. Moving on to the test drive: I slowly drove it out of the neighborhood and came out onto a main road close to home. The car seemed to run fine at this point, no stalling or anything, i then get it up to speed and i could feel hesitation. I thought maybe if i gave it some throttle then it would clear up, i get to about 3rd gear (about 30-40 mph) and I could hear a popping sound but not like a back fire. Kinda like popcorn but very faint, i get to a stop sign and the cars dies, I attempt to start with no avail, the car would start and idle but only for a second, the only way to keep an idle was to hold down the throttle. So i babied it back home (approx 1 mile). I pull it into the garage and the first thing i check was the wiring harness to the ECU. After peeling back the carpet i discovered i have an N333 ECU with the rtek 1.7. I went to pocketlogger.com and after reading what they posted about running 550cc injectors that engine damag could result, i really hope not.
I guess my question is do you guys think ill be ok once i replace the 2 550cc secondaries to 750cc? Or do you guys think i fucked it up by only driving a mile maybe even less? Are there any quick tests i can do to check the health of the engine? I pulled the lower spark plugs and they were brand new when installed, they were damp, not wet and had mild carbon build up that easily wiped clean. I dont have a rotary compression tester and im hesitant to use a piston engine compression tester. Any help would be greatly appreciated.
Last edited by DankestKush; 12-29-16 at 04:43 PM.
12-28-16, 10:23 PM
#3
Using a piston engine tester will show you if it is indeed blown.
https://www.rx7club.com/2nd-gen-arch...urate-1099047/
You will at least know where you stand by performing it any way you can. There are many resources available to testing compression. I hate to say it, but you just gotta give it a shot.
The Rtek 1.7 needs more fuel as it is changing the timing. If the fuel required is not provided it would be incredibly likely (especially with your description) that the motor has blown. But the compression test is exactly where I would start. I'm sure most any on here would agree with that based on your description.
https://www.rx7club.com/2nd-gen-arch...urate-1099047/
You will at least know where you stand by performing it any way you can. There are many resources available to testing compression. I hate to say it, but you just gotta give it a shot.
The Rtek 1.7 needs more fuel as it is changing the timing. If the fuel required is not provided it would be incredibly likely (especially with your description) that the motor has blown. But the compression test is exactly where I would start. I'm sure most any on here would agree with that based on your description.
12-29-16, 04:42 PM
#6
the car no injectors to start with, i put the 4 550's that the previous owner had provided. it just sucks cuz i never bothered to check the ecu untill i had an issue. only then is when i found out i had the rtek. damn well im hoping since the drive was short lived there may be a slim chance i could be okay. but like you said its prolly done.
12-29-16, 07:47 PM
#7
the Rtek wouldn't be what caused it, probably too many modifications and not enough support or an aging fuel system contribution.
generally if you can audibly hear the knock, it is a sign of timing way too far advanced, an improperly stabbed CAS could have caused it in conjunction with a lean issue. bout the only other time you will hear the knock is if you are sky high in boost somehow.
generally if you can audibly hear the knock, it is a sign of timing way too far advanced, an improperly stabbed CAS could have caused it in conjunction with a lean issue. bout the only other time you will hear the knock is if you are sky high in boost somehow.
Last edited by RotaryEvolution; 12-29-16 at 07:50 PM.
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12-30-16, 09:14 AM
#8
the Rtek wouldn't be what caused it, probably too many modifications and not enough support or an aging fuel system contribution.
generally if you can audibly hear the knock, it is a sign of timing way too far advanced, an improperly stabbed CAS could have caused it in conjunction with a lean issue. bout the only other time you will hear the knock is if you are sky high in boost somehow.
generally if you can audibly hear the knock, it is a sign of timing way too far advanced, an improperly stabbed CAS could have caused it in conjunction with a lean issue. bout the only other time you will hear the knock is if you are sky high in boost somehow.
01-08-17, 08:48 PM
#10
Ok so was finally able to have some time to at least turn the motor by hand and check it that way aka poor mans comprrssion test. Now I don't exactly know what type of "pssst" or "wooosh" sound i should be looking for or if what my motor is doing sounds good or bad. If anyone after watching the clip can enlighten me as to if it's sound Like it should.
01-13-17, 03:46 PM
#14
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Someone please correct me if I'm wrong, I haven't done this myself but usually people say to remove the valve at the end of the fitting. Many people though also say you can just hold down the relief valve while testing.
So maybe try holding how the relief valve for your first test if you don't want to jump in and disassemble the tester?
So maybe try holding how the relief valve for your first test if you don't want to jump in and disassemble the tester?
01-13-17, 04:43 PM
#15
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remove the valve at the end of the fitting/inside the hose, install tester on trailing plug, dissconect CAS connector, fully depress accelerator pedal while cranking 5-10 sec while looking for even needle bounces on your comp gauge. Good luck
