new motor... Breaking up under ANY load.
09-14-14, 12:04 AM
#1
Need some input. Built a tii block, RA classic seals, solid corners, Race springs, big streetport, big exhaust ports etc.. basically, nicely built motor.
Specs:
Rtek 1.7
Rewired Walbro 255
550/750 injectors
Modified stock fuel rails
Adjustablr fpr
44psi base fuel pressure
Stock s5 turbo/ported wastegate
8psi max boost
No emissions
Stock 7/9 spark plugs
Stock coils
Cruising is fine, idle is fine, wot is fine under light load in 1st/2nd
Cruise AFR: ~14-15.5
Boost AFR: ~10.8-11.2
Now the issue is, when I go for a hard pull in any gear, it will break up, and seemingly detonate. Even when afr's are in the low 11's. Actually it will even break up in vacuum!!! I can NOT figure out wtf the problem is. Tried two different harnesses, And rechecked every ground.
My car just breaks up under load, no idea why. Afr is fine, and actually quite rich. What could I be over looking???
Specs:
Rtek 1.7
Rewired Walbro 255
550/750 injectors
Modified stock fuel rails
Adjustablr fpr
44psi base fuel pressure
Stock s5 turbo/ported wastegate
8psi max boost
No emissions
Stock 7/9 spark plugs
Stock coils
Cruising is fine, idle is fine, wot is fine under light load in 1st/2nd
Cruise AFR: ~14-15.5
Boost AFR: ~10.8-11.2
Now the issue is, when I go for a hard pull in any gear, it will break up, and seemingly detonate. Even when afr's are in the low 11's. Actually it will even break up in vacuum!!! I can NOT figure out wtf the problem is. Tried two different harnesses, And rechecked every ground.
My car just breaks up under load, no idea why. Afr is fine, and actually quite rich. What could I be over looking???
09-14-14, 10:48 AM
#5
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test the plug wires, they should be under 16k Ohms per wire, new are like 6-7k. the more resistance the wires have the less power you get at the spark plug.
09-14-14, 03:16 PM
#6
Wires are in stalled correctly, but really old. Just bought new ones, they'll be here in two hours at the parts store.
Hopefully that has something to do.with it. Also gonna try and take the fuel pressure down a few psi. Maybe 41-42psi
Hopefully that has something to do.with it. Also gonna try and take the fuel pressure down a few psi. Maybe 41-42psi
09-14-14, 03:31 PM
#7
Hopefully not your problem, but our S5 TII we purchased new had a similar problem back in 2001.
I could drive normally, actually get on it in 1st/2nd with no problems, actually get it up to 80/90 no problem, but under hard acceleration in higher gears it would kick back.
Took it to Dave at KD and he could get it to act up when on the street, but on the machine with the test equipment hooked up, it would run normally and show no problems. After about 2 weeks, he finally got the answer and faxed me the readout where one rotor had a significant drop, broken seal. This was with a stock components.
Installed a Mazda remanufactured and good 'til this day.
I could drive normally, actually get on it in 1st/2nd with no problems, actually get it up to 80/90 no problem, but under hard acceleration in higher gears it would kick back.
Took it to Dave at KD and he could get it to act up when on the street, but on the machine with the test equipment hooked up, it would run normally and show no problems. After about 2 weeks, he finally got the answer and faxed me the readout where one rotor had a significant drop, broken seal. This was with a stock components.
Installed a Mazda remanufactured and good 'til this day.
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09-14-14, 04:18 PM
#8
Hopefully not your problem, but our S5 TII we purchased new had a similar problem back in 2001.
I could drive normally, actually get on it in 1st/2nd with no problems, actually get it up to 80/90 no problem, but under hard acceleration in higher gears it would kick back.
Took it to Dave at KD and he could get it to act up when on the street, but on the machine with the test equipment hooked up, it would run normally and show no problems. After about 2 weeks, he finally got the answer and faxed me the readout where one rotor had a significant drop, broken seal. This was with a stock components.
Installed a Mazda remanufactured and good 'til this day.
I could drive normally, actually get on it in 1st/2nd with no problems, actually get it up to 80/90 no problem, but under hard acceleration in higher gears it would kick back.
Took it to Dave at KD and he could get it to act up when on the street, but on the machine with the test equipment hooked up, it would run normally and show no problems. After about 2 weeks, he finally got the answer and faxed me the readout where one rotor had a significant drop, broken seal. This was with a stock components.
Installed a Mazda remanufactured and good 'til this day.
HIGHLY doubt that is my issue, but I will definitely keep that in the back of my head if we simply just can't figure this thing out. Thanks for the heads up, because I was unaware of that even being possible
just got a universal orielly one..
09-14-14, 07:54 PM
#14
Probably not your problem, but just wanted to give a little more info. Only put about 2000 miles per year on the car, but I tried for 6 months looking for a solution, finally gave up and took it to Dave. Yes, with the cracked seal there was no loss of compression, idle was fine and start was instantaneous, just as it had always been since new, only noticeable under heavy load in higher gears. That was the problem, Dave ran the engine in the garage under load and could not duplicate the problem and all readouts with the equipment indicated that there was no problem, but it could be duplicated on the street under load.
Don't hold me to this, but I believe it was a corner seal.
Good luck.
09-14-14, 09:49 PM
#15
After the engine install, I didn't have a pill in the line for years and no problems.
Probably not your problem, but just wanted to give a little more info. Only put about 2000 miles per year on the car, but I tried for 6 months looking for a solution, finally gave up and took it to Dave. Yes, with the cracked seal there was no loss of compression, idle was fine and start was instantaneous, just as it had always been since new, only noticeable under heavy load in higher gears. That was the problem, Dave ran the engine in the garage under load and could not duplicate the problem and all readouts with the equipment indicated that there was no problem, but it could be duplicated on the street under load.
Don't hold me to this, but I believe it was a corner seal.
Good luck.
I think it MAY be a coil. but totally not sure.
Could the TPS be causing such extreme break up?
09-14-14, 10:33 PM
#16
Once above 3000 rpm or so the TPS plunger is fully extended so if you're having problems above that the only way the TPS would interfere is if the signal to the ECU was not constant which it should be was being interrupted. If it was cutting out and the voltage signal dropped it would basically tell the ECU to cut fuel. If you unplugged the TPS it would default to full range such that the ECU would think you are operating over 3k rpm.
09-15-14, 07:09 PM
#18
Rotary Enthusiast
Your timing is off.
Check your trailing plug wires as well and make sure they aren't reversed, I've seen probably 20 cars where people get them backwards and it causes exactly this.
Check your trailing plug wires as well and make sure they aren't reversed, I've seen probably 20 cars where people get them backwards and it causes exactly this.
09-16-14, 06:37 AM
#19
+1 for ignition not properly adjusted or a vacuum leak in a really bad place!
Batterycables tightened down on the battery?
offtopic: i made 335rwhp with my trailing/leading wires crossed before my engine started to ping during tuning :-D
Batterycables tightened down on the battery?
offtopic: i made 335rwhp with my trailing/leading wires crossed before my engine started to ping during tuning :-D
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