Poor cylinder compression on new built motor - what to do?
07-13-2007, 04:33 PM
#22
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Originally Posted by Cannysage
I run the unichip on mine, and although it's not the greatest, it gets me by. I'm running 650cc injectors with it. I'm at 12psi putting out decent power.. do you have the stock ignition? unichip to utec isn't much of an upgrade imo.. I'm going fcon next year and turning up the boost a notch or 2..
07-13-2007, 05:52 PM
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Originally Posted by westpak
For those levels you are probably right, wont see much benefit, but if going up in boost might as well put that money towards the Fcon if you can.
And I probably will - the ECM upgrade is contingent upon what GTM finds.
Then I'll have a UniChip and new UTEC setup for sale - that should cover about 1/3 the FCon setup, I suppose...
07-14-2007, 03:39 AM
#25
higher hp levels have been achieved with the same ecm you are using, thus i am not sure throwing more money at the problem will get you any closer to your goal. looking at the mechanical facts of the comp tests (even though abit varied) the number 1 cylinder would still not be creating a dip like that. do you have a blow-by oil tank? if so, how much and how long does it take for oil to build up in it(there is a reason jdm uses clear lines on the pcv lines). that is a good indication of blow-by created by non-sealing rings. if oil is getting into the lines that is visible [stock valve covers have chambers to help collect it as is]. mechanically, you have shown a problem, thus electonic solutions will not cure it. not saying there is conscience fault, but parts failure is something that can happen to the best of us.
todd has done quite a few motors by now and don't think he would overlook ringend gaps or position of them or machining overlooks.
todd has done quite a few motors by now and don't think he would overlook ringend gaps or position of them or machining overlooks.
07-14-2007, 09:03 AM
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Originally Posted by overZealous1
higher hp levels have been achieved with the same ecm you are using, thus i am not sure throwing more money at the problem will get you any closer to your goal. looking at the mechanical facts of the comp tests (even though abit varied) the number 1 cylinder would still not be creating a dip like that. do you have a blow-by oil tank? if so, how much and how long does it take for oil to build up in it(there is a reason jdm uses clear lines on the pcv lines). that is a good indication of blow-by created by non-sealing rings. if oil is getting into the lines that is visible [stock valve covers have chambers to help collect it as is]. mechanically, you have shown a problem, thus electonic solutions will not cure it. not saying there is conscience fault, but parts failure is something that can happen to the best of us.
todd has done quite a few motors by now and don't think he would overlook ringend gaps or position of them or machining overlooks.
todd has done quite a few motors by now and don't think he would overlook ringend gaps or position of them or machining overlooks.
I certainly don't want to be guilty of fingerpointing by ay means. My inbox was overwhlemed with positive feedback about Todd's motors before pulling the trigger; I'm confident that it was built correctly and that things will be resolved appropriately if the motor is found to be at fault.
Of course, I'm hoping it's something less invasive such as a faulty VVT solenoid, a timing issue, etc. There were numerous P0300 codes coming from the car during tuning, both here in Scottsdale and at GTM. The car did not smoke, nor consume any appreciable oil within the 500 mi. between oil changes, no leaks, no sounds, no knock. Turbo is in great condition; backpressure shouldn't be an issue with the current exhaust setup and EGTs that were shown while being dyno'd.
Hence, that's why she's at GTM - I don't have the means, patience or equipment to properly identify the issue as to why it's losing power after 5500rpms, why increasing the boost does nothing, and why she's throwing so many misfire codes with both the UniChip and UTEC.
I imagine I'll hear from Sam by sometime next week.
Last edited by JoeDirtPharmD; 07-14-2007 at 09:13 AM.
07-14-2007, 09:40 AM
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Originally Posted by JoeDirtPharmD
That I could recall, the oil catch can was not collecting much, if anything, in the way of blow-by - I would need GTM to chime in on that since I haven't had my hands in the car for a little over a month except for an oil change.
I certainly don't want to be guilty of fingerpointing by ay means. My inbox was overwhlemed with positive feedback about Todd's motors before pulling the trigger; I'm confident that it was built correctly and that things will be resolved appropriately if the motor is found to be at fault.
Of course, I'm hoping it's something less invasive such as a faulty VVT solenoid, a timing issue, etc. There were numerous P0300 codes coming from the car during tuning, both here in Scottsdale and at GTM. The car did not smoke, nor consume any appreciable oil within the 500 mi. between oil changes, no leaks, no sounds, no knock. Turbo is in great condition; backpressure shouldn't be an issue with the current exhaust setup and EGTs that were shown while being dyno'd.
Hence, that's why she's at GTM - I don't have the means, patience or equipment to properly identify the issue as to why it's losing power after 5500rpms, why increasing the boost does nothing, and why she's throwing so many misfire codes with both the UniChip and UTEC.
I imagine I'll hear from Sam by sometime next week.
I certainly don't want to be guilty of fingerpointing by ay means. My inbox was overwhlemed with positive feedback about Todd's motors before pulling the trigger; I'm confident that it was built correctly and that things will be resolved appropriately if the motor is found to be at fault.
Of course, I'm hoping it's something less invasive such as a faulty VVT solenoid, a timing issue, etc. There were numerous P0300 codes coming from the car during tuning, both here in Scottsdale and at GTM. The car did not smoke, nor consume any appreciable oil within the 500 mi. between oil changes, no leaks, no sounds, no knock. Turbo is in great condition; backpressure shouldn't be an issue with the current exhaust setup and EGTs that were shown while being dyno'd.
Hence, that's why she's at GTM - I don't have the means, patience or equipment to properly identify the issue as to why it's losing power after 5500rpms, why increasing the boost does nothing, and why she's throwing so many misfire codes with both the UniChip and UTEC.
I imagine I'll hear from Sam by sometime next week.
again, I hope it is resolved easily for you, Sam is an excellent mastermind in engine diagnostics, he will figure it out. good luck, and keep me posted.
TODD
07-14-2007, 10:22 AM
#28
maybe a compound problem is happening, and you may have a small boost leak too. hopefully it gets found and doesn't just cure itself. there are good gremlins just as there are bad ones. sometimes if you leave something alone for awhile, you simply turn it on and it is fixed! hahhaa. it falls right in line with the "grab a bigger hammer" theory, lol. good luck. post up any finds.
07-14-2007, 05:50 PM
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Originally Posted by 350zDCalb
the symptoms are a bit puzzling..as if the #1 cylinder was the main culprit, one would assume that the power would be affected earlier in the power band, and at even lower boost pressure... the fact that it doesnt make any more power with the higher boost setting could point towards a cylinder that is at its threshold and loses pressure when the boost increases past a certain point- possibly a cylinder/ring issue when you had a rich condition in the beginning..but still unlikely...typically a washed cylinder wall that results in poor ring seating will consume oil, may smoke, and will likely produce other symptoms at lower power levels and lower rpms iwhile under boost...
again, I hope it is resolved easily for you, Sam is an excellent mastermind in engine diagnostics, he will figure it out. good luck, and keep me posted.
TODD
again, I hope it is resolved easily for you, Sam is an excellent mastermind in engine diagnostics, he will figure it out. good luck, and keep me posted.
TODD
In my head, with the abrupt power drop at a specific RPM range, and the inability to make power with addt'l boost, the light backfiring it makes during idle, the misfire codes, etc., it makes sense to me to be either a timing issue, or a VVT solenoid issue that's exacerbating the issue in the upper powerband?
The rich condition reared it's head during the break-in process only when I was > 75% throttle and 4500+rpms. I ended up staying out of it > 50% throttle due to this, and when I ran a borescope when I did the first compression check, the cylinder wall looked great. Of the three oil changes she's had thus far (50 mi, 250mi, 1000 mi) the oil looked great, no smell, no loss of volume, etc. RC Engineering's flow report didn't show any anomalous activity with the injectors, so that's been ruled out. The tuner in Scottsdale really had me invested in the idea is was a spark issue, that's why I ended up adding the HKS Ignition Amp and new plugs - to no avail.
Another thing I can't wrap my head around - that with the increase in boost and high RPMs, I wouldn't imagine air having the opportunity to blow past the rings without seeing some symptoms yet still result in a significant power decrease? It's hard for me to say that one cylinder is causative of this. Now if all 6 were toast, maybe...? But they're likely not?
I wish I had taken a Dyno from GTM - maybe they can post one up - the power drop off is very abrupt. I don't have any information in front of me to say when the variable timing solenoid kicks in in the VQ35DE, but it looks suspect from my non-professional perspective. Whether that has any culpability as far as being unable to make use of increased boost pressure - I dunno.
Of course, it may be multifactorial as well. I'm going stir crazy waiting to see what the diagnosis is in the meantime...
Last edited by JoeDirtPharmD; 07-14-2007 at 05:52 PM.
07-15-2007, 02:49 PM
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if the boost is rising and the power is not... maybe the turbos effeciency is maxed, maybe a turbo issue...even if cyl #1 is poor for whatever reason, the other 5 cylinders are still going to see a greater pressure and make more power..unless the turbo is just blowing hot air...(=more boost and same power)
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07-16-2007, 09:10 AM
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Originally Posted by 350zDCalb
if the boost is rising and the power is not... maybe the turbos effeciency is maxed, maybe a turbo issue...even if cyl #1 is poor for whatever reason, the other 5 cylinders are still going to see a greater pressure and make more power..unless the turbo is just blowing hot air...(=more boost and same power)
TODD
TODD
Originally Posted by JoeDirtPharmD
I guess the good news is the car makes a tad over 400rwhp at 4500rpm at 9psi. However, the horsepower curve takes a dump after 5500 rpms - looks almost parabolic in nature - down to low 300's by 6500 rpms
This isn't the turbo. I'll put $100 bucks on that. At 9psi, the power is spot on. But the power falling flat at 5500rpm is intriguing to say the least. Remember that he's pushing a GT35R. Those turbos don't even get into peak efficiency until 20-25psi. If the engine is found to be solid with no issues. Look at the wastegate / external wastegate piping. The boost is going somewhere. The question is where...
07-16-2007, 12:21 PM
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Originally Posted by TENGAI
This isn't the turbo. I'll put $100 bucks on that. At 9psi, the power is spot on. But the power falling flat at 5500rpm is intriguing to say the least. Remember that he's pushing a GT35R. Those turbos don't even get into peak efficiency until 20-25psi. If the engine is found to be solid with no issues. Look at the wastegate / external wastegate piping. The boost is going somewhere. The question is where...
when i said turbo issue, i was meanign to imply in addition, the accessories that control the boost around the turbo as well, ie- wastegate, etc... i agree...
07-18-2007, 11:00 PM
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if it not making more power on more boost, its most likely pulling timing and your have reached your octane ceiling. as far as the uteck the other members are rite it not much better than the unichip and almost as archaic to tune. my suggestion is Cobb access port , i know it not on the shelves yet but you cant beat it, hks is no even close, no piggyback can be and for a hand full of Qualified tuning shops, full control will be available including cam advanced tables which means those overly expensive cams that made next to no power can finally be utilized and forced inductions cars can reach full potential.
