Post engine rebuild help. Sorry for the wall of text, but I am at a loss.
10-20-2015, 10:26 PM
#1
Registered
Thread Starter
Post engine rebuild help. Sorry for the wall of text, but I am at a loss.
Hey everybody, I’m having a couple of very worrisome issues with my RX8. I have already searched (using the site: // search: method) but I am not finding any helpful information.
The issues-
1) The car will not idle. When I keep some throttle applied, it runs great. But as soon as I take my foot off of the gas for any length of time it dies. Sometimes it will do a little flutter around 500 RPM, but it still dies.
I have tried to drive it a bit, but even after a mile or so (after I let it get to temperature) if I let off the gas it will die.
2) After it dies, it will not start for hours. I usually end up just trying again the next evening. When I try to start it after about 24 hours, it fires right up; but once it dies (even if it ran for literally 2 seconds) it will not start again.
3) Overheating. I know there is a lot of doom and gloom about the RX8 coolant temperature needle. Twice now I have seen my temp needle start to wiggle from normal temperature. As soon as I see it budge, I let off the gas and the car shuts off (dies) and I check it out. The first time this happened was when I was trying to figure out the idle issue- I held the RPMs at around 3500 for about 1 hour and 15 minutes, just sitting in neutral. Some coolant boiled out, but I suspect this was likely due to my having misread those stupid markings on the passenger side of the bottle and overfilled it. I realize this overheat was 99% caused by me sitting on the gas for so long with no air moving through the radiator or engine bay. However, this evening the needle wiggled again. I was trying to drive it again, with the plan being that I would try to let off the throttle after I reached the garage again. A car cut me off, I let off the gas and applied clutch/brake, and the car died. I noticed after it died that the temp gauge bumped up an increment.
For both overheats, the gauge bumped up 1 notch (the second time) and then just over halfway (the first time) before I shut the car off. That said, I know the temp gauge is horrible in our cars.
I understand that new seals and reused housings can have weak initial compression until they wear together, but shouldn’t it still be able to idle at least a little bit?
The car-
I just rebuilt the engine, myself. I reused the rotors (apex grooves were within ‘tolerance’), rotor housings (looked great, though I did not have them lathed or measured properly), end and intermediate irons (also looked great, though I did not have them lathed) and eccentric shaft. All of the seals/springs/gaskets were replaced. The spark plugs are new, and I have pulled them and made sure they were still clean.
I also street ported the intakes/exhaust housings.
I have the Racing Beat Street Ported tune (Their V3 tune).
I also installed Racing Beat steel braided Oil Cooler lines.
The car had (while it was still running) and still has:
AEM CAI
BHR ignition coils and wires
A gutted catalytic converter
It is a 2004, 6-speed manual, 6 port/high power, and the engine HAD 117k miles.
I have also cleaned the MAF and made sure the vacuum lines were connected and going in the right direction.
There was about ¾ tank of 8 month old gas, I pumped out ¼ of it and then added an octane booster, an enzyme to help old fuel regain its octane, and then added new gas. I have only ever used 91 octane at minimum, and usually fill up with 92 octane.
I made sure the coils are connected to the appropriate spark plugs.
The car seems to run well while gas is applied, so I do not think it is an issue with the injectors.
About me- I am 26, have a Bachelor’s degree in Physiology and am now going back for a B.S. in Mechanical Engineering (
The issues-
1) The car will not idle. When I keep some throttle applied, it runs great. But as soon as I take my foot off of the gas for any length of time it dies. Sometimes it will do a little flutter around 500 RPM, but it still dies.
I have tried to drive it a bit, but even after a mile or so (after I let it get to temperature) if I let off the gas it will die.
2) After it dies, it will not start for hours. I usually end up just trying again the next evening. When I try to start it after about 24 hours, it fires right up; but once it dies (even if it ran for literally 2 seconds) it will not start again.
3) Overheating. I know there is a lot of doom and gloom about the RX8 coolant temperature needle. Twice now I have seen my temp needle start to wiggle from normal temperature. As soon as I see it budge, I let off the gas and the car shuts off (dies) and I check it out. The first time this happened was when I was trying to figure out the idle issue- I held the RPMs at around 3500 for about 1 hour and 15 minutes, just sitting in neutral. Some coolant boiled out, but I suspect this was likely due to my having misread those stupid markings on the passenger side of the bottle and overfilled it. I realize this overheat was 99% caused by me sitting on the gas for so long with no air moving through the radiator or engine bay. However, this evening the needle wiggled again. I was trying to drive it again, with the plan being that I would try to let off the throttle after I reached the garage again. A car cut me off, I let off the gas and applied clutch/brake, and the car died. I noticed after it died that the temp gauge bumped up an increment.
For both overheats, the gauge bumped up 1 notch (the second time) and then just over halfway (the first time) before I shut the car off. That said, I know the temp gauge is horrible in our cars.
I understand that new seals and reused housings can have weak initial compression until they wear together, but shouldn’t it still be able to idle at least a little bit?
The car-
I just rebuilt the engine, myself. I reused the rotors (apex grooves were within ‘tolerance’), rotor housings (looked great, though I did not have them lathed or measured properly), end and intermediate irons (also looked great, though I did not have them lathed) and eccentric shaft. All of the seals/springs/gaskets were replaced. The spark plugs are new, and I have pulled them and made sure they were still clean.
I also street ported the intakes/exhaust housings.
I have the Racing Beat Street Ported tune (Their V3 tune).
I also installed Racing Beat steel braided Oil Cooler lines.
The car had (while it was still running) and still has:
AEM CAI
BHR ignition coils and wires
A gutted catalytic converter
It is a 2004, 6-speed manual, 6 port/high power, and the engine HAD 117k miles.
I have also cleaned the MAF and made sure the vacuum lines were connected and going in the right direction.
There was about ¾ tank of 8 month old gas, I pumped out ¼ of it and then added an octane booster, an enzyme to help old fuel regain its octane, and then added new gas. I have only ever used 91 octane at minimum, and usually fill up with 92 octane.
I made sure the coils are connected to the appropriate spark plugs.
The car seems to run well while gas is applied, so I do not think it is an issue with the injectors.
About me- I am 26, have a Bachelor’s degree in Physiology and am now going back for a B.S. in Mechanical Engineering (
10-21-2015, 03:04 AM
#2
Driving my unreliable rx8
Post engine rebuild help. Sorry for the wall of text, but I am at a loss.
An engineer with bs is always the case., lol.
I've got 2 things for you to check first. With the car cool take off the radiator cap and start it. Then watch a min for coolant to boil. If it does you have a bad coolant seal. If not good.
Then check your fuel trimsand maf. Maf should bearound 5.5. If fuel trims are over 10 you have a problem. If maf is good and trims are way out then you miss wired your injectors.
I've got 2 things for you to check first. With the car cool take off the radiator cap and start it. Then watch a min for coolant to boil. If it does you have a bad coolant seal. If not good.
Then check your fuel trimsand maf. Maf should bearound 5.5. If fuel trims are over 10 you have a problem. If maf is good and trims are way out then you miss wired your injectors.
10-21-2015, 11:48 AM
#3
Registered
Thread Starter
Thank you for the reply! Yeah I was in 'over explain' mode so I added the BS ha. I will check what you said this evening.
How do I go about checking the fuel trims and measuring the MAF grams? I forget if an OBDII reader can do this.
How do I go about checking the fuel trims and measuring the MAF grams? I forget if an OBDII reader can do this.
10-21-2015, 11:58 AM
#5
Driving my unreliable rx8
Nah the BS comment was a joke. I think theres quite a few engineers around here.
you need an obd scanner to pull that data. If you don't have one you can find a cheap bluetooth dongle online and use the torque app. there's tons of data here on the club about it. You might beable to get autozone to use one that pulls that data. Just check it at idle should be fine.
you need an obd scanner to pull that data. If you don't have one you can find a cheap bluetooth dongle online and use the torque app. there's tons of data here on the club about it. You might beable to get autozone to use one that pulls that data. Just check it at idle should be fine.
10-22-2015, 07:35 PM
#6
If I had to guess, I'd say two things:
1) You may have not reassembled the auxiliary engine parts correctly. You might have a vacuum hose out of place, a sensor partially connected, etc. I've heard it's easy to mix up the two fuel lines so check that out when you have the time.
2) You made a mistake on your rebuild. Maybe one of your coolant jackets are twisted or pinched.?There's a C02 coolant tester kit which you can buy. It's a small vial of liquid that sucks the "air" from you heating system.If it detects exhaust molecules, it will change colors. Not sure of the name of the product. You can find on google easy.
Anyways, they're only $40 or so dollars, and are good to have in general. If option 1) doesn't work out, definitely perform basic tests on the engine like cooling system tests and compression tests. If you do have coolant in your engine, it can really damage the internals, so you should take care of it asap.
Good luck.
1) You may have not reassembled the auxiliary engine parts correctly. You might have a vacuum hose out of place, a sensor partially connected, etc. I've heard it's easy to mix up the two fuel lines so check that out when you have the time.
2) You made a mistake on your rebuild. Maybe one of your coolant jackets are twisted or pinched.?There's a C02 coolant tester kit which you can buy. It's a small vial of liquid that sucks the "air" from you heating system.If it detects exhaust molecules, it will change colors. Not sure of the name of the product. You can find on google easy.
Anyways, they're only $40 or so dollars, and are good to have in general. If option 1) doesn't work out, definitely perform basic tests on the engine like cooling system tests and compression tests. If you do have coolant in your engine, it can really damage the internals, so you should take care of it asap.
Good luck.
Thread
Thread Starter
Forum
Replies
Last Post
ShellDude
RX-8 Parts For Sale/Wanted
6
10-14-2015 07:42 PM