Single turbo fd help
08-24-15, 09:12 PM
#1
Junior Member
Thread Starter
Single turbo fd help
Hey guys, I have a single turbo 13b rx7 with a garret gt40r turbo running around 10 pounds of boost with a power fc. Yesterday i was cruising on the back roads, and was going up a slight hill in 3rd gear, gave it some wot and around 5k she made a cracking noise and seemed as if she topped out. I immediately let go of the gas and made it over the hill took it out of gear and she just died. She never went lean as far as I could tell. Tried to restart her, but a no go, she would just crank but not catch. Eventually just push started her and made it back to my house. Checked the oil and she was good, still had good pressure, no vacuum leaks, but now just wouldn’t start, and if it did it wouldn’t idle would just die. So i though she was flooded (but then again how) so I tried unflooding her, cleaned the spearkplugs, but still no go. I eventually got her started by just giving her a lot of gas on the pedal, and adjusted the idle screw for her to idle at around 1600. Now if I drive her, she stumbles and has weak power below 3000k but above 3k she is fine. Her idle is very choppy almost as if she has a misfire. I know I should do a compression check, and I will do it tomorrow when it is light out. But beside me blowing a seal, what could it be?
Last edited by R7rexy; 08-24-15 at 09:14 PM.
08-24-15, 09:27 PM
#2
Hey guys, I have a single turbo 13b rx7 with a garret gt40r turbo running around 10 pounds of boost with a power fc. Yesterday i was cruising on the back roads, and was going up a slight hill in 3rd gear, gave it some wot and around 5k she made a cracking noise and seemed as if she topped out. I immediately let go of the gas and made it over the hill took it out of gear and she just died. She never went lean as far as I could tell. Tried to restart her, but a no go, she would just crank but not catch. Eventually just push started her and made it back to my house. Checked the oil and she was good, still had good pressure, no vacuum leaks, but now just wouldn’t start, and if it did it wouldn’t idle would just die. So i though she was flooded (but then again how) so I tried unflooding her, cleaned the spearkplugs, but still no go. I eventually got her started by just giving her a lot of gas on the pedal, and adjusted the idle screw for her to idle at around 1600. Now if I drive her, she stumbles and has weak power below 3000k but above 3k she is fine. Her idle is very choppy almost as if she has a misfire. I know I should do a compression check, and I will do it tomorrow when it is light out. But beside me blowing a seal, what could it be?
08-24-15, 09:33 PM
#3
Junior Member
Thread Starter
Sounds like it went lean and took out an apex seal. But if compression checks out I would verify spark it sounds to be like a misfire of some sort. If the plugs got flooded just grab a new set of plugs 9"s all around and see if that helps. Yeah I would start there first and report back.
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08-25-15, 10:13 PM
#8
that's really not a great test but it does tell you the compression is low. Most likely you chipped a seal. The culprit is almost always a tuning issue or a problem with the fuel/ignition system. Find the issue before throwing a motor in there or it will be likely to happen again. If you can get the car to me I'd be more than happy to look at it. You can also pm me your full setup and I'll see if anything draws any red flags.
08-25-15, 11:35 PM
#10
Junior Member
Thread Starter
that's really not a great test but it does tell you the compression is low. Most likely you chipped a seal. The culprit is almost always a tuning issue or a problem with the fuel/ignition system. Find the issue before throwing a motor in there or it will be likely to happen again. If you can get the car to me I'd be more than happy to look at it. You can also pm me your full setup and I'll see if anything draws any red flags.
08-26-15, 01:23 AM
#11
Junior Member
Thread Starter
It's been tuned by previous owner and about 30k. I want to sell her since I don't even have time to sleep with my current schedule and work on her. 13k very negotiable seems reasonable.
08-26-15, 07:54 AM
#12
Pm me info on your car. Miles, year, and mods if you could.
08-26-15, 10:03 AM
#13
I hate to say it but nothing is bulletproof, especially since you lost compression. I use RX Parts seals almost exclusively. I have yet to see a set break but like most aftermarket seals, run the EGTs too high and they will warp. You also absolutely MUST premix with them if you want the motor to last. If the seals did warp the good news is there will likely be no internal damage. Change the seals and springs and you should be good to go.
09-01-15, 08:07 PM
#14
Junior Member
Thread Starter
Hey, so I have a feeling that my compression readings might be a little off and that my problem lies within my coil packs or plug wires. I checked my trailing spark and its nice and powerful, but my leading spark for the front is weak, and the rear is similar. Could account for the car being hard to start cold and hot, and super rich afr readings. Car seems to misfire in low rpms, but runs perfect above 3k.
09-01-15, 08:35 PM
#15
Hey, so I have a feeling that my compression readings might be a little off and that my problem lies within my coil packs or plug wires. I checked my trailing spark and its nice and powerful, but my leading spark for the front is weak, and the rear is similar. Could account for the car being hard to start cold and hot, and super rich afr readings. Car seems to misfire in low rpms, but runs perfect above 3k.
You have a chipped seal if you have 60psi showing on one rotor and 100 on the other for example. I think its bad news.
09-01-15, 09:15 PM
#16
Junior Member
Thread Starter
My rear and front were above 95 less then 300 miles ago, and the car was not pushed, oil was in check, i just dont see how both of the rotors would chip their seals.
09-01-15, 09:51 PM
#17
You said you were doing an uphill pull when it happened. More load in a high gear is typically when these things happen. I think youve blown the motor from what you were doing, the way you say it drives and the compression #s.
A weak battery could not turn the engine over enough to create compression. But consistently getting that much higher on one side is bad news. Can anyone help you run the test? You need to take out the check valve or perhaps holding the release button would work. Someone should be watching the gauge needle carefully as the engine cranks. You should see 3 distinct pulses. With 1 chipped apex seal you'll see 1 higher reading and two lower readings. Like 100-60-60. I bet there are vids on the forum or YouTube of examples.
Let us know...
09-01-15, 10:52 PM
#18
Junior Member
Thread Starter
I think you're right its rare for both rotors to blow seals. However that one rotor is half what that other is seems telling. Unless you're doing the test completely wrong or the tester is broken.
You said you were doing an uphill pull when it happened. More load in a high gear is typically when these things happen. I think youve blown the motor from what you were doing, the way you say it drives and the compression #s.
A weak battery could not turn the engine over enough to create compression. But consistently getting that much higher on one side is bad news. Can anyone help you run the test? You need to take out the check valve or perhaps holding the release button would work. Someone should be watching the gauge needle carefully as the engine cranks. You should see 3 distinct pulses. With 1 chipped apex seal you'll see 1 higher reading and two lower readings. Like 100-60-60. I bet there are vids on the forum or YouTube of examples.
Let us know...
You said you were doing an uphill pull when it happened. More load in a high gear is typically when these things happen. I think youve blown the motor from what you were doing, the way you say it drives and the compression #s.
A weak battery could not turn the engine over enough to create compression. But consistently getting that much higher on one side is bad news. Can anyone help you run the test? You need to take out the check valve or perhaps holding the release button would work. Someone should be watching the gauge needle carefully as the engine cranks. You should see 3 distinct pulses. With 1 chipped apex seal you'll see 1 higher reading and two lower readings. Like 100-60-60. I bet there are vids on the forum or YouTube of examples.
Let us know...
09-02-15, 10:24 AM
#20
Will you please tell us more about the setup?
What is the Air Fuel Ratio? When you say it is tuned rich, what do you mean? an 11.0 AFR in 3rd while you're at WOT?
Do you know the timing advance on the leading and split at 10psi ~5k rpm?
What is your fuel pump setup? What are you injectors? Are you using 93 octane?
What is the Air Fuel Ratio? When you say it is tuned rich, what do you mean? an 11.0 AFR in 3rd while you're at WOT?
Do you know the timing advance on the leading and split at 10psi ~5k rpm?
What is your fuel pump setup? What are you injectors? Are you using 93 octane?
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