I have a 1988 Mazda RX-7 Turbo 10thAE and the thing is just drinking gas likes it water, I mean, it's ridiculous. I know that the car has a turbocharger and all, but it's taking way more than it should. To give you an idea of how bad this thing is sucking up gas, I filled the tank 2 days ago, and 80 highway miles later, a little more than half the tank is gone.

Some other symptoms are that the idle is very rough, it doesn't stay on when the engine is cold, I have to rev it for about a minute or two before it idles on it's on and then it idles rough. I plan on changing the TPS (Haven't checked it yet) soon, but could this cause the gas to go that fast?

Can someone please point me toward the right direction? What could be the problem and what should I check? Anyone know a solution?

Especially with gas prices the way they are these days, I really need a fix. Thanks in advance.

 

well,

you do have to do a couple things before you can see what the problem is.

1. check TPS
2. clean injectors
3. get a lighter right foot
4. check grounds
5. check for leaks,
6. replace fuel filter (in tank and external)


thats all i can reccomend for right now

 

^^^^ I agree and would add MAKE SURE YOU DONT HAVE ANY FUEL LEAKS as 1st priority. Also check water temp sender for the ecu. Not sure about turbo, but it is on the t-stat housing. If it is unplugged or fucked up it will run stupid rich. Also maybe get a new O2 sensor and spark plugs. How about running the diagnostic test too? All you need is 2 leds from radioshack, and you will need it to do the tps the correct way.

 

+1 to the vac leaks. I had crappy idle and mileage once. I had a friend ride with me so I could have him listen to the suction, blew an intercooler soft pipe that was leaking (that's how I found out what the problem was) and we tightened it all back up. Everything was fine after that.

 

easy way to check is to spray w-40 around the vac lines and if the idle changes you have a leak.

 

You need to measure fuel consumption more accurately. Fill the tank, zero the odometer, drive 'til it's empty and refill it. Divide the distance travelled by how much it took to refill the tank.

It sounds like the thermowax has beem removed from the TB, causing the bad cold idle. This will have little if any effect on average fuel consumption. It could also be a faulty or disconnected thermosensor on the back of the water pump. A rough idle when warm could be from a vac leak. Common culprits are a split TID, broken solenoid nipples and cracked vac hoses.

No, but it can mess up the idle so check it anyway. Don't replace it unless you prove it's actually faulty.

The thermosensor could be faulty but this will not cause rich mixtures. If the ECU detects a faulty or missing thermosensor it will use a default value of 176degF. This will cause poor running then cold because the mixture's too lean for a cold engine, but it will run normally when warm.

The O2 sensor has only a small effect on mixtures and only when cruising. It cannot cause excessive fuel consumption even when disconnected.

Checking for ECU error codes is a good idea, but the TPS should be set with a DMM instead of the LED's. The LED's aren't very accurate.

 

isn't that roughly 10mpg? I haven't really been keeping watch on it but I get that rate some times and mine's an n/a lol.

actually come to think of it, my car eats up about 2 gallons per 30 some miles

 

Hey, sorry to revive an old thread, but this is exactly what is happening with my car. S4 with an s5 t2 swap. Does anyone have some more insight on this problem?

 

Wow 11 year old thread revived. I was 13 lol