'86 RX7 Rally Car

Awesome!! great technique

In reply to java230:

I guess I should have started with that, huh?

Of course, I thought I had this issue nailed down a couple other times already, but this was definitely a problem, since it didn't take much in the way of movement to screw up the way the car ran.

Fidelity/other rotards- am I going to hurt this thing running with the MAP unplugged? I've already ordered a replacement so it can sit and wait if it has to, but I'd like to keep putting miles on it. It should just run rich, right?

I'm sure it will be fine.

I just did a bunch of testing with the map sensor on my S4 Rx7.

When I had mine unplugged, the car lost 7 to 13 hp throughout the rev range.

With it plugged in without having a restrictor in the line, I gained some of the lost HP back.

With it plugged in and the proper restrictor in the line, (basically how the car is supposed to operate) the car made decent power.

With the MAP sensor electrically plugged in but the vacuum line capped, I made the most HP. I got about 3 HP throughout the rev range by capping the line. The AFR is kinda sketchy between 6500 and 7500 in this configuration.

All this testing was done on a dyno the same day and each run was backed up and verified.

Just some info for ya!

Rob R.

In reply to wvumtnbkr:

Well that's certainly an interesting result- what was your "kinda sketchy" AFR? Lean, rich, bouncing all over the place?

New MAP sensor installed- pretty sure it didn't fix it. It did its' thing once right when I first started driving- a big 1 second total loss of power around 5k rpm at WOT in 2nd- then I couldn't get it to do it again. The ECUs don't "learn" or anything right?

When I returned, I noticed the water pump is now leaking. Good that I'm finding it now instead of in the middle of a stage I guess.

Well, there's always Jason's Volvo 240 all ready to go, lol......

Yeah yeah, berkeley you I know. If he had put that thing up for sale 6 months ago I'd be busy building a turbo Volvo motor right about now.

¯\_(ツ)_/¯ wrote: Yeah yeah, berkeley you I know. If he had put that thing up for sale 6 months ago I'd be busy building a turbo Volvo motor right about now.

Perked attention... Volvo stage car for sale...?

Thanks Ross

Ross413 wrote:

¯\_(ツ)_/¯ wrote: Yeah yeah, berkeley you I know. If he had put that thing up for sale 6 months ago I'd be busy building a turbo Volvo motor right about now.

Perked attention... Volvo stage car for sale...? Thanks Ross

Ross, send me an email at my username @yahoo.com and I'll send you the information. It's one of our mid-atlantic folks

It was nice and warm out yesterday so I did a few more things to the RX7 while it's waiting for the water pump to arrive.

Stashed the warning triangles behind the navigator's seat:

Added a HF toolkit and made a wheel chock into a spare tire tiedown- this not only gives me a wheel chock for when I have to change a tire, but also keeps it from making annoying clanky noises.

Then I put together a "kludge kit." Bungees, duct tape, electrical tape, silicone tape, zip ties, safety wire, fuses, various caps and hose clamps, quick splices, WD40, gasket maker, 5 minute epoxy, spare fuel pump, spare belts, and of course a towel.

It all fits nicely in this little bag which lives next to the "human kludge kit" a.k.a. first aid box.

Some of the first aid stuff needs to be updated, and I'm debating carrying a few more spares (control arm, ball joint, U joint, halfshaft).

In reply to ¯_(ツ)_/¯:

Like 13.9 or 14.0:1.

Also, I would be checking your sensor grounds. I believe 2 of the wires that go to that sensor are grounds.

Or it could be a bad connection at the AFM.tugging the map wires could cause the AFM wires to jiggle a little.

Never, ever, no matter what, forget your towel.

In reply to wvumtnbkr:

AFM has been thoroughly investigated. I may run new grounds for the ECU, since the only ones I haven't cleaned are under the intake manifold and that seems like not a fun thing to pull apart.

What's strange is I can't find any accounts of others having this same issue- lots of hesitation or temporary rev limit issues, but no random cutting out and coming back a second later. Makes me wonder if it's actually the ignition, or the ECU.

I've never heard of one of these ecus going bad.

In would be adding a few specific grounds. One from battery to chassis on drivers side. One from that point to under the intake manifold where the injector grounds are located. Then, I go from the ecu grounds to the firewall. All using big gauge wire.no more concern about grounds.

That one under the intake is important! I would check the entire harness actually. Unwrap it and replace any crispy wires...

Now that I am thinking more about your issue, it could be a dying tpS sensor...

Hey I recognize that WD can!!

In reply to java230:

I have a few ideas for some of those lights too but haven't really felt like messing with wiring.

Based on what wvumtnbkr said I checked the TPS. The values are supposed to be 1k ohms resistance at closed throttle, and 4.5k ohms at WOT. I measured 6 ohms closed and 17 ohms WOT. No I did not forget a k

I'm going to bring my multimeter to work tomorrow to check the calibration against a much better, 100x more expensive meter.

Tested my multimeter at work- it needed a fuse, I'm stupid. Will recheck tonight.

The big thing to look for is any spikes or continuity issues throughout the sweep.

Retested with (now functional) multimeter. 1.3k ohms closed, 5.4k ohms open, smooth sweep throughout travel. Good enough I think.

Yep. Good enough.

Now go add a good ground to your injector grounds.

Do you still have all the emissions rack crap under the upper intake? Get rid of it and simplify. Then add grounds.

I can take pics of mine if you want.

In reply to wvumtnbkr:

One step at a time

Mine still has all its' emissions junk- I wouldn't mind a picture of your setup.

wvumtnbkr wrote: I've never heard of one of these ecus going bad. In would be adding a few specific grounds. One from battery to chassis on drivers side. One from that point to under the intake manifold where the injector grounds are located. Then, I go from the ecu grounds to the firewall. All using big gauge wire.no more concern about grounds. That one under the intake is important! I would check the entire harness actually. Unwrap it and replace any crispy wires... Now that I am thinking more about your issue, it could be a dying tpS sensor...

Ive had injector drivers fail on an ECU before.

If that's the case I can send you one of my spares. I'll run it in my car first to see if its good.