today i replaced the MAF with a new one. no change in the acceleration problem. i also had to readjust the idle a little bit, but i got it stable now. i think the next thing i'm going to do is look at that fuel pressure regulator and fuel pump. i'm going to borrow a fuel pressure gauge and see what i find. i don't know where to hook it up exactly...before or after the injectors? i'll try to figure it out. also, what's a good pressure that i should be reading??

 

Hook it up right after the fuel filter. About 45psi cold, 35 warmed up. You can create an exhaust leak without removing the o2 by loosening the 2 nuts on the front converter.

 

Well, fuel pressure seems to be good. I did notice some other things that may or may not be a big deal. For instance....

1- I noticed that one of the electrical connections to a fuel injector was loose. With the car already running, I decided to disconnect it. Nothing changed. So I decided to also disconnect the other connector that goes to the other injector. Still no change. Which makes me ask, are there only 2 fuel injectors on this thing? With the car still running and both injectors electronically disconnected, I decided to take the car out for a little spin. It drove the same as it always does. Weird. What are those electrical connectors supposed to be doing?? Do I have bad injectors??

This led me to another observation...

2- I saw that the transistor that makes it go from lean to rich had been turned to the rich side almost completely. With the injectors connections back ON, I turned the transistor slowly back towards the middle. The engine began to idle very erratically until it finally stalled. It will only run in the rich position.

So this made me realize that my idle is pretty screwed up....

3-When the engine is cold, it won't idle unless I keep giving it gas. The RPM's just go up and down, and up and down. Once the engine is warm though, it idles okay...but I noticed that it will start to sputter about every 10 seconds....then go back to a normal idle. I only noticed this when the hood was up. I couldn't tell it was doing this when I was driving.

A friend told me that the EGR valve might be stuck. I don't know too much about those so he may be right. Who knows?? What do you all think??

 

Just an update....

I bought new injectors and a fuel regulator. When I pulled the old injectors, the small screen that is in between the injector and the engine on one of them was really clogged. I tried to clean it out the best I could. Do they come out at all? I will probably take them out again and try to clean them this weekend.
Still didn't solve the problem though.
I have really noticed that the engine is running super rich. Seems to be getting spark okay. Maybe not enough air? If I baby the motor up past 3500 rpm's, it really starts to blow out blue smoke. And if I just hammer down the gas pedal, it seems to be flooding the engine. It doesn't stall though....just stays at the same rpm. Almost like it's starving for air.

I ordered a used egr valve.... apparently they don't make new ones any more. Any tips on changing this thing out? I think I have to remove the intake manifold to get to it if I'm not mistaken.
Who knows, maybe the egr valve is the problem?
Even at idle (which is very rough at the moment), the engine sputters alot. It will rev up for a second...and then sputter back down. Rev up, sputter down. ....And it will only idle if the engine's warm. When it is cold, it will start up, stay at about 3000 rpm's for 10 seconds maybe....and then just drop down to 0. Weird eh?

 

It has 4 injectors. 2 are under the upper intake.The ones you can see are secondary injectors. You may have a lower intake leak which is a lot bigger job than the upper. If you see blue smoke the oil metering pump could be bad, usually due to water pump leak onto it which can also take the ECU out. The adjustment you played with is for idle mixture,it only turns 1/4 turn and if forced further will short the ECU. If you do need a new ECU and yours is a manual shift trans the ECU for auto trans and convertible models will work and increase performance since they are heavier and are set for more injector volume.

 

Wow! Those other 2 injectors were really hidden down in there! I took off the upper intake, put on some new injectors and egr valve, and cleaned up everything. I put it all back together and now the car won't start. It turns over, but turns over really easily - like it's not getting any compression. I pulled the plugs out and they were soaked in gas. I let them sit overnight and plan to put them back in this morning. I don't know what the deal is. I had a great seal on the upper intake when I put it back on. I didn't hear any air leaking out anywhere. Hmmm.... we'll see what happens today!

 

Pretty common. Pull the top 2 plugs and squirt a little oil or atf in there. Reinstall the plugs and hold the gas pedal to the floor and crank til it starts,hold the rpms up to 3k or so for a minute. It is flooding out and washed the apex seals out. If no glory that way pinch off the fuel line from the fuel filter while someone cranks it. Always hold the gas pedal to the floor when they flood like that.

 

Thank you! Thank you! Thank you! I thought the ol' RX-7 had finally croaked! I did what you said and put some oil in the top 2 holes of the 2 spark plugs. I could hear the engine turn over differently after I did that. Luckily, I have a toggle switch for my fuel pump. I turned it off and turned the engine over. It took it awhile, but the car finally started! Thank you so much! With the new EGR valve, the engine idles ALOT smoother, however, I still have the acceleration problem at 3500 RPM's. It just will NOT accelerate past 3500 unless I have the accelerator at 25% or less.
I am just glad to have a running car again...
Thank you again!

I am still open to any ideas about what to replace next. Eventually, I will find it, but I'm running out of stuff to replace.

 

There is a small vacuum hose on the passenger side running to the fenderwell. I think it goes near the resistor for idle mixture you spoke of in an earlier post. Anyway that hose has an orifice inside it.If the hose has been replaced and now no longer contains the orifice it causes driveability problems. The TPS is important for performance also. Has this car run this way since you bought it? Is it possible someone replaced the ECU with one from a junkyard? They look the same but differ in fuel volume ouput for the injectors. If they put an ECU from a manual transmission in it it will be a dog since it is an auto trans. Also i think the altitude compensator is inside the ECU on those. If it sticks it can cause performance problems.

 

Where is the ECU located? I think I remember seeing it at one point. Is it the square box that's under the air intake?