Help , GSLSE wont go pass 4k RPM
01-04-16, 09:41 PM
#1
Help , GSLSE wont go pass 4k RPM
GSLSE wont go past 4 k RPM . history of the car engine rebuild last month street ported , new oem fuel filter , injectors cleaned , new coolant temp sensor, new ignition cap , rotor and spark plugs cables, 6th port actuator removed , header and emissions & cats removed. car was running fine for 150 miles after the rebuild but now it wont go past 4 k rpm . i have check all the connections i removed the entire intake twice to double check everything. im thinking maybe AFM is bad, any suggestions
Last edited by Boriquaguerrero; 01-05-16 at 07:16 PM.
01-05-16, 12:28 AM
#3
84SE-EGI helpy-helperton
First off, what's an 'actuator' that you removed?
If the car ran fine for 150mi after you got it all back together, that tells me you had it right at one time in the recent past. Backtrack to anything you've done since then and have another look. Some things that jump to mind;
1) Fuel filter - replaced because...??? If clogged, then your new filter may be clogged as well. Once replaced, you get better fuel flow, which can pick up more tank contaminants and clog your new filter, but unlikely. If just PM, look elsewhere.
2) Fuel pump - my SE pump is still going strong at 222k mi, so it's a remote possibility that it's failing. Testing fuel pressure at the rail or the firewall connection to the rail should show you 45-60psi. If significantly below that, could be pump failing, lines failing, or a crimp in the feed. Check the return, too - they run right next to each other.
3) Fuel Pressure Regulator - on the rail is a diaphragm which closes on intake vacuum under heavy load, shunting down the return line (i.e., effectively increasing pressure at the injectors). If the FPR vacuum line came loose you'd have a vacuum leak (bump idle, surging, etc.), along with low fuel pressure all the time. Unsure if that would prevent rev-ing being 4k, but you need fuel to accelerate. While you're in there, check the injectors with a long Stethescope rod and listen for the tell-tale 'click' which increases with throttle position.
4) Ignition changes - check your ignitors. If you still have Tach signal to ECU, then you have good Trailing Spark (ignitor). If Tach is dead, then you have no trailing spark which improve emissions. Dead Leading spark will cause the engine to run very poorly and possibly prevent rev-ing to the higher RPM range. Easy test: swap ignitors and see if the symptoms change. If yes, bad ignitor now in trailing position. If no, ignitors are not the problem.
5) Exhaust - you said you removed header/emissions/cats, but what did you put on in place? Check for restrictions in the exhaust flow.
6) Air Filter - check it and make sure you didn't suck a bird up in there or something. And, because every RX7Club list should have 7 items...
7) Throttle Body - make sure you're not binding something on the throttle body that's preventing the throttle linkage from moving. Check the OMP rod, for instance.
Good luck, and please report back with what you find. Half the time, people post with problems, we all jump in to help, and then they disappear without a trace...
If the car ran fine for 150mi after you got it all back together, that tells me you had it right at one time in the recent past. Backtrack to anything you've done since then and have another look. Some things that jump to mind;
1) Fuel filter - replaced because...??? If clogged, then your new filter may be clogged as well. Once replaced, you get better fuel flow, which can pick up more tank contaminants and clog your new filter, but unlikely. If just PM, look elsewhere.
2) Fuel pump - my SE pump is still going strong at 222k mi, so it's a remote possibility that it's failing. Testing fuel pressure at the rail or the firewall connection to the rail should show you 45-60psi. If significantly below that, could be pump failing, lines failing, or a crimp in the feed. Check the return, too - they run right next to each other.
3) Fuel Pressure Regulator - on the rail is a diaphragm which closes on intake vacuum under heavy load, shunting down the return line (i.e., effectively increasing pressure at the injectors). If the FPR vacuum line came loose you'd have a vacuum leak (bump idle, surging, etc.), along with low fuel pressure all the time. Unsure if that would prevent rev-ing being 4k, but you need fuel to accelerate. While you're in there, check the injectors with a long Stethescope rod and listen for the tell-tale 'click' which increases with throttle position.
4) Ignition changes - check your ignitors. If you still have Tach signal to ECU, then you have good Trailing Spark (ignitor). If Tach is dead, then you have no trailing spark which improve emissions. Dead Leading spark will cause the engine to run very poorly and possibly prevent rev-ing to the higher RPM range. Easy test: swap ignitors and see if the symptoms change. If yes, bad ignitor now in trailing position. If no, ignitors are not the problem.
5) Exhaust - you said you removed header/emissions/cats, but what did you put on in place? Check for restrictions in the exhaust flow.
6) Air Filter - check it and make sure you didn't suck a bird up in there or something. And, because every RX7Club list should have 7 items...
7) Throttle Body - make sure you're not binding something on the throttle body that's preventing the throttle linkage from moving. Check the OMP rod, for instance.
Good luck, and please report back with what you find. Half the time, people post with problems, we all jump in to help, and then they disappear without a trace...
Last edited by LongDuck; 01-05-16 at 12:31 AM.
01-05-16, 11:11 AM
#4
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Has the tank ever been cleaned? If not, there is a real good possibility that there is rust inside. The fuel filter is actually on the discharge side of the fuel pump. If your tank has rust issues the pump won't be able to draw enough fuel and that could be where your problem lies. This is more likely to show up at higher RPM's. I agree with LongDuck regarding the pump - test the fuel pressure AND the volume output. Even if you are getting enough pressure, the volume may not be enough to keep up.
Last edited by andernamen; 01-05-16 at 11:14 AM.
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01-06-16, 12:30 PM
#8
Yep, or gum and varnish. Mine had that, and some small rust chips. The in-tank strainer isn't really very effective. I added a see-through plastic filter in front of the pump, and it filled up in 75 miles! Then I swapped filters; it lasted another 225 miles or so. The third filter has held up fine but started looking full at about 500 miles so I'm on my fourth filter now.
My tank should probably get dropped and thoroughly cleaned.
My tank should probably get dropped and thoroughly cleaned.
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