car is running really bad under 4k
12-05-09, 02:22 PM
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car is running really bad under 4k
I have tried a search and can't find anything that helps. I have a stock 87 that was running good. I put a Lucas Fuel Treatment in with my gas and it all went down hill. I have used the Fuel Treatment before and on different vehicles and haven't had a problem. Now when the car is cold it will run fine but it will now get high on the temp gauge and as soon as it starts to come down it will start running bad. Any speed under 4k rpm and the car surges real bad and I can't hold a steady speed. I have cleaned the plugs and put a new fuel filter I thought that it might be the catalytic converter so I unbolted the exhaust and drove it but it still is running the same. What next?.... Fuel tank? Fuel pump? Injectors? ......HELP PLEASE
12-05-09, 07:37 PM
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I just went through the same thing. Mine would not rev past 4500RPM and progressively got worse over the course of 3 weeks. By week 3 the car was very difficult to start, especially when it was hot. I could not rev past 3500RPM and top speed was about 45MPH. It also sounded like a car wash pressure washer, when you squeeze the handle, while I tried to accelerate.
On Monday I had the car parked on top of a puddle and when I came out of the store I could see the exhaust blowing into the puddle from underneath the passenger seat area.
When I got home I raised the car as high as I could safely get it. Once underneath I could clearly see that I had blown the gasket between the 2nd pre converter and the main catalytic converter. To my surprise I found that just 4 bolts held the main catalytic converter in place. I unbolted the converter and chunks of stuff started falling out.
Assuming that the converter would be between $200 - $300 I decided to chip away at the rest of the stuff inside. Once it was all removed I bolted the Main Converter back in place. The car fired rite up, so I took it on a test drive. Let me tell you, it was like a whole new car. I had hard acceleration from 4000 RPM to 6000RPM; it felt like a turbo kicked in!
Latter on that night I went to start it and, Click, Click, Click. I must have burned out the starter while it was hard to start. While pricing starters on line I also checked the main Catalytic Converter Price. It was only $85.00. At the auto parts store I ordered a new starter with a lifetime warranty for $95.77 including tax. I bolted it in 2 days later and it fired rite up again.
It has been 3 days now with no problems, knock on wood. Next week I plan to purchase the new catalytic converter and gaskets.
Sorry for the long post. Good luck with your RX7
On Monday I had the car parked on top of a puddle and when I came out of the store I could see the exhaust blowing into the puddle from underneath the passenger seat area.
When I got home I raised the car as high as I could safely get it. Once underneath I could clearly see that I had blown the gasket between the 2nd pre converter and the main catalytic converter. To my surprise I found that just 4 bolts held the main catalytic converter in place. I unbolted the converter and chunks of stuff started falling out.
Assuming that the converter would be between $200 - $300 I decided to chip away at the rest of the stuff inside. Once it was all removed I bolted the Main Converter back in place. The car fired rite up, so I took it on a test drive. Let me tell you, it was like a whole new car. I had hard acceleration from 4000 RPM to 6000RPM; it felt like a turbo kicked in!
Latter on that night I went to start it and, Click, Click, Click. I must have burned out the starter while it was hard to start. While pricing starters on line I also checked the main Catalytic Converter Price. It was only $85.00. At the auto parts store I ordered a new starter with a lifetime warranty for $95.77 including tax. I bolted it in 2 days later and it fired rite up again.
It has been 3 days now with no problems, knock on wood. Next week I plan to purchase the new catalytic converter and gaskets.
Sorry for the long post. Good luck with your RX7
12-06-09, 10:16 AM
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It sounds like the fuel cleaner may have dislodged crud that otherwise would not be an issue, and sent it right through the injectors. Make some checks for things like vacuum leaks and a misadjusted TPS, dirty BAC, etc., but it sounds like you should have your injectors professionally cleaned.
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12-11-09, 05:56 PM
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The 2 you see are the secondary injectors. They come on line at 3800 rpm. The other two are your primary injectors which are on the engine under the intake manifold.
12-14-09, 09:44 AM
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12-16-09, 04:33 PM
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I just really don't want to pull the injectors and that not be the problem. It is my only means of transportation right now.... and im really not sure that is what it is going to be. Like I said it runs normal before it warms up, no surging at all...then the temp will go up..(way up..Higher than normal) Then the temp drops and it runs like crap? That wouldn't be injectors would it? Any leads would be appreciated.
01-01-10, 12:13 PM
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This makes more sense than anything else to me.
Good call Aaron
I'm new to this rotary thing but I am not new to emmissions.
This is a problem that has always plague us with carbs ecspecially the holly double pumpers and anything else that has to rely on air to fuel mixture.
1) You put lucas fuel treatment into the tank and it did its job. The questions is or should be "Do you need another bottle"
The Lucas cleaned or loosened some crude within your emmissions and your emmissions are set perfectly for a dirty system. I myself would get another can of the lucas and run it through to make sure all the debri is cleaned out.
2)After throroughly cleaning out your system, recheck and reset your fuel to air mixture. (How?)
If the cleaner worked, You are dumping more fuel and maybe a more accurate spray pattern.
I would first try adjusting the throttle position sensor, and 9 times out of 10 your idle will also be increased once thats done because with a clean system you are dumping more fuel. No Blockages.
So just go through the normal emmissions checklist. You may find out that your MPG's will go up.
BTW- Get you a can of carb cleaner and clean out your throttle body while you're at it.
Good call Aaron
I'm new to this rotary thing but I am not new to emmissions.
This is a problem that has always plague us with carbs ecspecially the holly double pumpers and anything else that has to rely on air to fuel mixture.
1) You put lucas fuel treatment into the tank and it did its job. The questions is or should be "Do you need another bottle"
The Lucas cleaned or loosened some crude within your emmissions and your emmissions are set perfectly for a dirty system. I myself would get another can of the lucas and run it through to make sure all the debri is cleaned out.
2)After throroughly cleaning out your system, recheck and reset your fuel to air mixture. (How?)
If the cleaner worked, You are dumping more fuel and maybe a more accurate spray pattern.
I would first try adjusting the throttle position sensor, and 9 times out of 10 your idle will also be increased once thats done because with a clean system you are dumping more fuel. No Blockages.
So just go through the normal emmissions checklist. You may find out that your MPG's will go up.
BTW- Get you a can of carb cleaner and clean out your throttle body while you're at it.
01-01-10, 01:08 PM
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01-01-10, 01:37 PM
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Well I did try putting a second bottle of the Lucas And now the car will barley go. I towed it to my dads garage and am getting ready to pull the injectors....any tips..tricks to make the process smooth???
01-01-10, 02:34 PM
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O.k. What is the green (check valve?) under the intake ..where it bolts to the throttle body? Could this be the culprit that is making my car run (and almost not run?)
01-02-10, 10:57 AM
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There are about 6 million green check valves on the FC. You are going to need to be more specific, but to answer your question, no. A failed check valve won't cause the car to run this badly. Many of the check valves are simply part of the emissions system.
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