GSL SE stutter, performance is crippled
01-28-12, 12:22 PM
#1
GSL SE stutter, performance is crippled
Hey hope everyone's doing well,
I have a 1985 SE that had been sitting for 7-8 years and maybe 6 months ago I got it running. It's a beautiful beast, in the 90's J at RX for your 7 installed a new street-ported 13b. That engine has maybe 60k miles on it now; it's strong but the systems powering it need a little TLC. The coolant was dried up and my fuel system was a mess. The fuel system has been replaced fully (injectors were cleaned by a shop).
My main concern is a stutter at full throttle; once the vehicle has warmed up a little. The stutter mainly happens when taking off, around 3-4k, it'll drop out and then come back to life (the tach falls a bit then returns to where it was). Occasionally power will dip a little around 5-6k WOT but never the stuttering. The other issue with the stutter is that in the Arizona summer it gets real hot and the car will perform worse and worse and after maybe 30 minutes of driving it will vapor-lock. When this happens the car will not start until it cools down fully. Once cool however, it runs fine. In fact, this winter has shown me what an awesome machine these are.
I have done some searching and my symptoms seem to match (1) secondaries not opening. (2) I am also concerned about my cooling system though, since it got the least attention I'll clean it up. (3) The final option would be my fuel pump or injector's not flowing properly once warm.
1) Secondaries: what I've read says that in the SE the Throttle Body Secondaries open up once the car is warm... My acceleration stutter happens when the car is warm around 3-4k RPM when the secondaries should be opening. There's a thermoswitch that opens them. I've read that it's controlled by vacuum and it's expensive ($50 from Malloy). Can I test to see if this is working? Has anyone cleaned it successfully?
2) Cooling: I plan to get the radiator hot-tanked, I'll also air out the coolant passages. I have read about a thermal switch on the water housing (engages the clutch fan)? Can I replace or clean that switch? It likely isn't functioning due to gunk. I can't buy the coolant switch from Malloy, is aftermarket ok? I hope, lol.
3) Fuel system: I have my doubts about the fuel system because the stutter in acceleration happens once the car is warm. Also because it's using an aftermarket 'Airtex' pump. I plan to install a FPR w/ gauge on the fuel line going 'in.' I won't regulate the pressure I just want to see if the aftermarket pump loses pressure once warm. If the pump is lame, it'll be upgraded. If not I can only imagine it's the injector's not flowing fully. However, I will not change anything here until the cooling system has been rejuvenated.
Thank you for all the reading! This is sort-of my game plan ^^ I am going to start with the radiator cleaning. Hopefully your extensive knowledge can help solve this and maybe rule out some of my ideas to save $$.
I have a 1985 SE that had been sitting for 7-8 years and maybe 6 months ago I got it running. It's a beautiful beast, in the 90's J at RX for your 7 installed a new street-ported 13b. That engine has maybe 60k miles on it now; it's strong but the systems powering it need a little TLC. The coolant was dried up and my fuel system was a mess. The fuel system has been replaced fully (injectors were cleaned by a shop).
My main concern is a stutter at full throttle; once the vehicle has warmed up a little. The stutter mainly happens when taking off, around 3-4k, it'll drop out and then come back to life (the tach falls a bit then returns to where it was). Occasionally power will dip a little around 5-6k WOT but never the stuttering. The other issue with the stutter is that in the Arizona summer it gets real hot and the car will perform worse and worse and after maybe 30 minutes of driving it will vapor-lock. When this happens the car will not start until it cools down fully. Once cool however, it runs fine. In fact, this winter has shown me what an awesome machine these are.
I have done some searching and my symptoms seem to match (1) secondaries not opening. (2) I am also concerned about my cooling system though, since it got the least attention I'll clean it up. (3) The final option would be my fuel pump or injector's not flowing properly once warm.
1) Secondaries: what I've read says that in the SE the Throttle Body Secondaries open up once the car is warm... My acceleration stutter happens when the car is warm around 3-4k RPM when the secondaries should be opening. There's a thermoswitch that opens them. I've read that it's controlled by vacuum and it's expensive ($50 from Malloy). Can I test to see if this is working? Has anyone cleaned it successfully?
2) Cooling: I plan to get the radiator hot-tanked, I'll also air out the coolant passages. I have read about a thermal switch on the water housing (engages the clutch fan)? Can I replace or clean that switch? It likely isn't functioning due to gunk. I can't buy the coolant switch from Malloy, is aftermarket ok? I hope, lol.
3) Fuel system: I have my doubts about the fuel system because the stutter in acceleration happens once the car is warm. Also because it's using an aftermarket 'Airtex' pump. I plan to install a FPR w/ gauge on the fuel line going 'in.' I won't regulate the pressure I just want to see if the aftermarket pump loses pressure once warm. If the pump is lame, it'll be upgraded. If not I can only imagine it's the injector's not flowing fully. However, I will not change anything here until the cooling system has been rejuvenated.
Thank you for all the reading! This is sort-of my game plan ^^ I am going to start with the radiator cleaning. Hopefully your extensive knowledge can help solve this and maybe rule out some of my ideas to save $$.
01-30-12, 11:06 PM
#2
84SE-EGI helpy-helperton
Hal's Radiator Service over on Glendale and 51st Ave is your best bet for radiator rod-out and repaint. They do a good job, and have done my SE radiator at least twice.
On the cut-out and vapor lock, this is certainly fuel related, and could be a combination of things starting from your Fuel Injection Fuel Filter (different than a low-pressure carb fuel filter), to the fuel lines, to the rail. The Fuel Rail is tucked under the intake manifold, but could certainly be getting some heat rising up from the exhaust system on hot days - I've never had an issue with vapor lock in 28 years with this car in the AZ summer, so I'm thinking it's something else in your case.
Also, the problem exhibiting itself on acceleration at 3-4k RPM seems like right about where the '6'-ports would be opening; if that's the case, then you may have an exhaust pressure leak that's allowing the '6'-ports to open and close rapidly (or open, then close completely) or a stuck '6'-port on the front or rear housing. These are operated by exhaust back-pressure, and there's a pressure port on your main cat that feeds this back to the lower intake manifold to operate the port actuators. Not a bad idea to clean those out, ensure that the little gaskets on the actuators are good, and generally, get it working like it should.
The fact that you have a street ported engine in there changes things a bit, as you're not dealing with stock tune anymore. That said, good luck, and keep it running,
On the cut-out and vapor lock, this is certainly fuel related, and could be a combination of things starting from your Fuel Injection Fuel Filter (different than a low-pressure carb fuel filter), to the fuel lines, to the rail. The Fuel Rail is tucked under the intake manifold, but could certainly be getting some heat rising up from the exhaust system on hot days - I've never had an issue with vapor lock in 28 years with this car in the AZ summer, so I'm thinking it's something else in your case.
Also, the problem exhibiting itself on acceleration at 3-4k RPM seems like right about where the '6'-ports would be opening; if that's the case, then you may have an exhaust pressure leak that's allowing the '6'-ports to open and close rapidly (or open, then close completely) or a stuck '6'-port on the front or rear housing. These are operated by exhaust back-pressure, and there's a pressure port on your main cat that feeds this back to the lower intake manifold to operate the port actuators. Not a bad idea to clean those out, ensure that the little gaskets on the actuators are good, and generally, get it working like it should.
The fact that you have a street ported engine in there changes things a bit, as you're not dealing with stock tune anymore. That said, good luck, and keep it running,
02-01-12, 01:19 AM
#3
Response to LongDuck
On the cut-out and vapor lock, this is certainly fuel related, and could be a combination of things starting from your Fuel Injection Fuel Filter (different than a low-pressure carb fuel filter), to the fuel lines, to the rail. The Fuel Rail is tucked under the intake manifold, but could certainly be getting some heat rising up from the exhaust system on hot days - I've never had an issue with vapor lock in 28 years with this car in the AZ summer, so I'm thinking it's something else in your case.
Also, the problem exhibiting itself on acceleration at 3-4k RPM seems like right about where the '6'-ports would be opening; if that's the case, then you may have an exhaust pressure leak that's allowing the '6'-ports to open and close rapidly (or open, then close completely) or a stuck '6'-port on the front or rear housing. These are operated by exhaust back-pressure, and there's a pressure port on your main cat that feeds this back to the lower intake manifold to operate the port actuators. Not a bad idea to clean those out, ensure that the little gaskets on the actuators are good, and generally, get it working like it should.
Also, the problem exhibiting itself on acceleration at 3-4k RPM seems like right about where the '6'-ports would be opening; if that's the case, then you may have an exhaust pressure leak that's allowing the '6'-ports to open and close rapidly (or open, then close completely) or a stuck '6'-port on the front or rear housing. These are operated by exhaust back-pressure, and there's a pressure port on your main cat that feeds this back to the lower intake manifold to operate the port actuators. Not a bad idea to clean those out, ensure that the little gaskets on the actuators are good, and generally, get it working like it should.
Judging by what you said I should replace my carb fuel lines with EFI lines. Would the difference between the two hoses matter a lot? How can I distinguish between a fuel injection filter and a carburated filter at the store? What kind of issues could there be with my rail? You're right though, the cutting out shouldn't be happening. My father drove this thing for over 10 years in the heat with no problems.
Also, the mechanic took temperature readings last summer trying to find the issue. He said my fuel shroud was erratic, the same temperature as my exhaust sometimes. I forgot to mention that before.
Thank you so much for the information about the suttering! I do have an exhaust leak and the gaskets on those port actuators aren't any good, I took them off recently to clean the LIM. I had no idea the exhaust is what opened them though. I ASSuMEd they were vacuum operated.
I have no real knowledge when it comes to cars. Before the RX-7 I had never worked on a car. I do my best to 'Search' but it only goes so far unless you know what to look for. Thank you for pointing me in the right direction.
02-03-12, 11:26 AM
#4
I had the same kind of problem
I had the same kind of problem, my Se had been sitting for a while. When I got it running again it ran well but when I filled the tank, it would only idle but the problem started out like you describe. Eventually, if I gave it gas, it would die. It turned out that there was a bunch of garbage in the gas tank. The SE has its fuel pump under the driver's side by the rear wheel with a sheet metal cover. If you take the fuel line off on the intake side of the fuel pump, there is a little screen that goes into the line and was clogged with junk. I cleaned it and it lasted a day or so.
So, I went to the local Kragen or whatever they're called today and bought a filter to go on the intake side of the fuel pump. It's a large line, I think it's 7/16" or 1/2" in size so they had to find a filter and lines that fit. They did, I put it in and it has been running for over 6 months. There's also a fuel filter on the other side that you might as well replace.
I also had a problem like that on an '80 12a and it turned out that the mechanical advance was seized. Took the dist apart and cleaned it up and it ran great and passed smog. I've got a spare SE dist in my hand and its mechanical advance is sticky so check that out as well.
I've screwed around with the secondary ports and have only noticed power loss; it still revved fine but they open around the RPMs you're having issues with so I don't know. I do know that it will run fine even if you take the lines off of the actuators and plug them with only a power loss when you're on it. So you could test it like that (by plugging the lines that go to the actuators). You should also be able to move the arm on the actuators through their arc smoothly. If either is seized, you need to fix that and check the actuators for leaks, too.
So, I went to the local Kragen or whatever they're called today and bought a filter to go on the intake side of the fuel pump. It's a large line, I think it's 7/16" or 1/2" in size so they had to find a filter and lines that fit. They did, I put it in and it has been running for over 6 months. There's also a fuel filter on the other side that you might as well replace.
I also had a problem like that on an '80 12a and it turned out that the mechanical advance was seized. Took the dist apart and cleaned it up and it ran great and passed smog. I've got a spare SE dist in my hand and its mechanical advance is sticky so check that out as well.
I've screwed around with the secondary ports and have only noticed power loss; it still revved fine but they open around the RPMs you're having issues with so I don't know. I do know that it will run fine even if you take the lines off of the actuators and plug them with only a power loss when you're on it. So you could test it like that (by plugging the lines that go to the actuators). You should also be able to move the arm on the actuators through their arc smoothly. If either is seized, you need to fix that and check the actuators for leaks, too.
02-03-12, 02:16 PM
#6
reply to rx7lives
I had the same kind of problem, my Se had been sitting for a while. When I got it running again it ran well but when I filled the tank, it would only idle but the problem started out like you describe. Eventually, if I gave it gas, it would die. It turned out that there was a bunch of garbage in the gas tank. The SE has its fuel pump under the driver's side by the rear wheel with a sheet metal cover. If you take the fuel line off on the intake side of the fuel pump, there is a little screen that goes into the line and was clogged with junk. I cleaned it and it lasted a day or so.
I've screwed around with the secondary ports and have only noticed power loss; it still revved fine but they open around the RPMs you're having issues with so I don't know. I do know that it will run fine even if you take the lines off of the actuators and plug them with only a power loss when you're on it. So you could test it like that (by plugging the lines that go to the actuators). You should also be able to move the arm on the actuators through their arc smoothly. If either is seized, you need to fix that and check the actuators for leaks, too.
I've screwed around with the secondary ports and have only noticed power loss; it still revved fine but they open around the RPMs you're having issues with so I don't know. I do know that it will run fine even if you take the lines off of the actuators and plug them with only a power loss when you're on it. So you could test it like that (by plugging the lines that go to the actuators). You should also be able to move the arm on the actuators through their arc smoothly. If either is seized, you need to fix that and check the actuators for leaks, too.
The actuators work well, I think LongDuck is right. I have an exhaust leak coupled with a vacuum leak at the actuators and thats preventing them from working properly. Last night I placed a Mazdatrix order for all the exhaust gaskets and the actuator gaskets and seals.
I did remove all the A/C (except for the interior box). I still have all the parts and I'm sure one day I'll have the funds to get it charged back up. Personally though, I've grown up in the heat and with the windows down it's not too bad.
02-07-12, 08:57 PM
#7
Sorry to double post. Today I got all the exhaust seals from Mazdatrix and a thermal switch at the throttle body from Malloy in. Installed everything and the RX-7 is FAST. I think I can do more by cleaning the actuators / actuator vacuum and air split (from cat) pipe.
Thank you LongDuck and rx7lives for helping out with my car.
Thank you LongDuck and rx7lives for helping out with my car.
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