wstrohm

I also had no driveability problems... car ran fine, before my current project screwed something up. So far I have spent $486 on various parts, the car is not running right, and I have no idea whether the fuel smell is gone, since it was intermittent in the first place. Finally got my pressure gauge/tee assembled and will check fuel pressure today. Also, wifey wants a new knock sensor... I'm guessing at least half the price of that is in the Mazda connector... too bad no universal product is available, similar to an O2 sensor.

wstrohm

So now the cost is up to 486+262 = $748 (added a knock sensor and oil fill pipe O-ring). Still have not found anything wrong. Installed new knock sensor, new platinum NGK plugs, new OEM plug wires, and a new O-ring for the oil fill pipe. The old plugs were really crudded over with black carbon, from the running check the first time I had reassembled the engine. Since all the plugs were black, I concluded that the problem is probably not a leaking or stuck injector, since I think then only one set of plugs (housing #1 or #2 but not both) would have been carboned up. (Unless, of course, all injectors are leaking or stuck!)

Latest tests:

1) Fuel pressure was tested with engine not running (obviously), F/P jumpered to ground, MityVac directly connected to FPR control line, gauge teed into input fuel hose. Results: Fuel pressure at 20" Hg vacuum = 34 psi. At atmospheric pressure = 43 psi. At 10 psi simulated boost = 51 psi. Pressure held up well, I thiought. After killing ignition at 34 psi, it stayed above 30 psi for 5-6 minutes, down to 20 psi in about 30 minutes, and down to zero in about 2 hours.

2) Checked TPS settings on bench (actually floor - no workbench space left). Results: Using a 5.0 volt power supply between the brown/white and brown/black terminals, at throttle fully closed (off fast idle cam), "3F" voltage was 1.44 volts, should have been 0.75 - 1.25 volts. "3G" voltage was 0.7 volts, should have been 0.1 - 0.7 volts. I adjusted the throttle butterfly stop for more closure (not the TPS), and wound up with "3F" = 1.1 volts and "3G" = 0.4 volts. All the other voltages were per the manual both before and after the adjustments.

3) Checked resistance of the intake air sensor: 2.33 K ohms, in spec.

4) Monitored voltage at the ECU pin 3E with ignition on, to look at the Water Thermosensor voltage. Measured 2.35 volts, which is good.

5) Plugged voltmeter into the "MEN" terminal of the Diagnostic Connector with "TEN" jumpered to "GND" to test the new knock sensor per the factory manual. Tapping the block with ignition on produced no change in my "digital" voltage reading. So this test failed, just as the old sensor did. I'm thinking the voltage spikes are too narrow for the meter to respond; maybe the manual should specify a scope instead of a voltmeter. Nothing on the AC position of the meter either, even with multiple tapping.

6) Checked the ignition wire harness on the piece that runs from the 6-prong connector to each of the primary coil connectors. All checked good, even when flexing the connectors & wires.


I cannot think of anything else to check before remounting the extension manifold (UIM). What else could cause very rich running? Anyone?????

wstrohm

Engine is back together and running fine now. Hard to believe that new plugs and wires are the reason, but I did nothing else since the last assembly except a lot of testing. There is no longer black smoke from the exhaust, and the car runs smoothly. Now to see if the fuel smell is permanently gone...

gracer7-rx7

iTrader: (16)

fwiw, gcthree "fixed" his issues somehow by re-installing the stuff he had removed. Can't really be sure if it was an issue of something not plugged in properly or misrouted or slightly loose but somewhere along the line after reversing the steps that got him into this similar mess, things started working properly.

Best of luck to you. This kind of work is well beyond my comfort level.

wstrohm

gracer7-rx7,

TNX! "Strange things are happening..."

Mahjik

iTrader: (1)

Congrats! Sometimes it just takes a 2nd reassembly to make things right.

wstrohm

Ran out of something to do & thought I would post back here as a wrap-up. Fuel smell is gone, car runs extremely smoothly, all is right with the world. However, in-town driving on the first fillup since the last put-together of the engine returned only 13.2 mpg (all in-town driving, generally off turbos). This is on new plugs, plug wires, and knock sensor.

Had a brief windows-down, on-the-road chat with an RX-8 owner/driver who previously owned 3 RX-7s, including one FD. He claimed no reliability problems with his FD. He said he ran 200K miles on its original engine, before buying the RX-8, and said the RX-8 is "more fun" than the FD. (No chance for me to ask "Why?")

dgeesaman

iTrader: (7)

200k on an original engine, wow. I've heard of only a couple cars going that high, and there are a lot of engine life threads buried in this forum.

Is the gas mileage still way down, or was it just the first tankful that low?

Dave

wstrohm

Dave,

We've only gone through that one tank so far. Typically the car gets 14-15 mpg in town, 21-23 on the road. Will wait until next tank to see, but can't see how it would improve much.

dgeesaman

iTrader: (7)

OK. When I got done with my injector cleaning job, my first tank ran at like 8mpg! Then it was back to the normal 14-18mpg. I have no idea where all that gas went.

Dave

HardHitter

iTrader: (4)

I have the same problem here as wstrohm. Strong fuel smell on the passenger side of the engine. I've been driving my car for 2-3 days since I've had the smell until it got stronger and haven't driven it since. Did a search and came up with this thread. About to go downstairs and start working on the car. I called Mazda and they have all the parts to replace the dampner (hopefully that being the problem)

Thanks again for everyone who helped wstrohm as it will hopefully be a great help for me. How's the car running wstrohm?

wstrohm

Runs fine, no fuel smell. Don't be surprised if you have to put that thing together twice to fix whatever gets screwed up during the first teardown! (Kidding, but that's what happened to me...) Be SURE to identify the junctions of all the vacuum hoses to the solenoid rack before you disconnect it. I used multiple colors of Testor's model paints. Watch out for hoses getting pinched under the AWS solenoid when you lower the UIM back into place.

HardHitter

iTrader: (4)

Yea so we got the uim off fine and everything. We don't know how to take off the solenoid rack and I've done a search and there was a picture with where to unscrew everything in one of the threads but the picture doesn't work anymore. Yea we are making sure we remmeber where each hose is going to so hopefully everything works out. We stopped working after not knowing how to get the solenoid rack off so if there is any other picture of where to remove everything it would be great help. I will tackle it tomorrow once I have information.

93ttwankel

Best picture I have, sorry. Just locate the brackets that hold the rack in place on the front and rear, then remove the screws that hold it in place. Front was easy rear was a huge pain in the ***. I would get a set of DALE CLARK checkvalves while you are in there. http://www.clubrx.org/default.asp?id...ntent=26&mnu=8

HardHitter

iTrader: (4)

Thanks for the picture, I have to disconnect all the hoses don't I? Or when I take out the whole rack, they all come together? I wish it was that simple.

HardHitter

iTrader: (4)

I'm starting to think I should of spent the $200 on labor for Rotorsport to fix my problem lol

I cannot get the rats nest out for some reason, I don't understand why it's not coming out. I removed the 4 bolts that are on the housing, then I removed the two bolts from the oil. Cut off 2 fuel hoses (going to replace them) took off the vaccum hoses and still it seems like it's stuck on something. Here are some pictures

HardHitter

iTrader: (4)

Alright, got the fuel rack out finally. There were two other screws holding in the oil filler neck and a few other hoses. Finally able to see the dampner under the crazy amount of wires.

Now how do I go about removing the FPD? While I'm under here I'm going to replace some of the stock hoses as they are hard as a rock.

Also, what should I do if some of the nozzles broke off with the hose while taking them off? Hopefully I'm not in a deep ditch now.

Mahjik

iTrader: (1)

Unbolt the primary fuel rail from the block. I would just go ahead and unbolt both fuel rails at this point and pull them out.

HardHitter

iTrader: (4)

While I'm here in a lot of the threads they were saying to send the injectors out to get cleaned and everything? Think I should have to do this? When I bought the car it had a 25k reman engine and that was last year, I put around 10k-13k on the car since owning it.

Thinking I might want to upgrade my fuel injectors since everything is torn apart?

Mahjik

iTrader: (1)

Well, just because the engine was replaced doesn't mean they also cleaned the injectors. Most places don't unless you specifically say to do so. If you don't know when they were last cleaned, you may as well send them out now. You'll also get no o-rings when they come back.

Do you have a 'need' for larger injectors?

HardHitter

iTrader: (4)

I have done all bolt ons, smic, full exhaust, pfc, pullys, clutch, etc etc and fuel and tune is the last thing to do for the stock twins. Looking to push boost to around 11-12psi. I think since the injectors are already out (or soon to be) I may as well send them off to rx7store to get them bored at to 1300cc? Keep primary's at 550cc and bring secondary to 1300cc. Fuel pump will be the last thing, but that is a lot easier to get to than the injectors.

Mahjik

iTrader: (1)

You don't need larger injectors for 11-12 PSI. You would also need a retune with larger injectors so you need to factor that into your costs.

HardHitter

iTrader: (4)

I'll go ahead and keep the stock 550cc/850cc injectors and keep the PFC on base map until I can get a tune for 11-12psi or would I be able to run base PFC @ those boost ratings with no problems.

Stock fuel system can handle up to 14psi correct?

Mahjik

iTrader: (1)

IMO, regardless of the boost you should have the PFC tuned for your car. IMO, its a waste to buy a programmable ECU and not have it tuned. Its no better than a M2 or Pettit ECU at that point. Having said that, you might check with others in the PFC forum on what to run on the base PFC map.

What the stock fuel system can handle will depend on what A/F ratios you can provide at 14 PSI. That's the important part. You can take the stock fuel system as far as your A/F will take you.

dgeesaman

iTrader: (7)

...which is all the more reason to get the existing injectors cleaned. Many aging injectors are flowing much less than 100%, and by getting them cleaned you'll help ensure that 14psi is a reachable limit with your existing gear.

Even if you don't push for higher boost, it's good to know that one of the rotors isn't running any leaner than it should be.

Dave