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iTrader: (7)

http://www.youtube.com/watch?v=L3zEi...ature=youtu.be

j9fd3s

iTrader: (3)

i'd say thats the TPS, but its kind of a shot in the dark... i like to adjust it with the 2 light method, as that is an OUTPUT from the ecu, the voltmeter method is an input to the ecu, and they vary

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iTrader: (7)

I'm sure it was my doing with the TPS, as it did not start until I started adjusting it. I went back over proper adjustment for the TPS and I have a little fixing to do. I'm sure my narrow band is off, and should take care of the surging issue.

In the mean time, since the MOP was out of spec, I've bought a replacement from a member on the boards and I'm going to do some more hunting for causes while its coming in the mail.


A though of mine today too was that perhaps there was interference from the alternator on the shielded wiring for the MAF causing issues, but I checked the shielding for continuity this evening and was only seeing .02ohms of resistance, so that rules that out.

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iTrader: (7)

I put the TPS to proper voltage today:

wideband: .84v
Narrowband: .95v

Immediately got rid of the surging, but it was still stuttering past 20% throttle and bogging like before if the engine saw any boost, but I figured perhaps I could get codes to show if I drove it around and put the engine under load.

Sure enough.

08 - Airflow Meter (AFM) - Basic Fuel Injection and fixed timing (Cripple mode)
10 - Intake Air Thermosensor (AFM) - Intake air fixed at 68F
11 - Intake Air Thermosensor (Engine) - Intake air fixed at 68F
18 - Throttle Sensor (TPS) Narrow Range - Fixed at full-open


I'm not sure about the IAT, it became unplugged while I was setting the TPS earlier, so that might've caused that.

But the TPS and MAF codes could easily explain for my problems..
Could also having the TPS being out of spec for voltage earlier account for the lack of codes before?

I'm going to recheck for codes after work, to rule out the IAT, but I'm (unfortunately) feeling pretty solid about the MAF, and perhaps the TPS.

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iTrader: (7)

The IAT on the engine, and the TPS are no longer showing up a codes and it dawned on me that I had unplugged both the IAT and the TPS during setting the TPS without disconnecting the battery.

Tomorrow I'm going to check the resistance of the MAF with the engine warmed up, since I haven't done that yet and will probably replace the wiring to the MAF, since it might have the possible cause to begin with.

j9fd3s

iTrader: (3)

yeah i like that! if the key is on, and you unplug something, it will set a code.

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iTrader: (7)

It's been a busy weekend unfortunately and haven't had a chance to confirm the codes yet. However, I went ahead and bought shielded wiring from a local electronics store and will be installing it tomorrow.

If the MAF does need to be replaced though, are they ECU specific? Or does it just have to be a Turbo MAF?

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iTrader: (7)

Pulled code 08 again today for the MAF, when it immediately stalled after starting it... however I was getting weird readings when checking for resistance.

Immediately after I pulled that code, I checked the MAF for resistance and was reading "Out of Limit" for BOTH the VS and VC with two different digital multimeters. (I made sure to test for ohms and kiliohms when appropriate as per the FSM, so I don't think its user error- but I suppose it could be.) I also made sure to test for voltage to the MAF, and was getting the correct voltage. However later in the day, I checked the resistance again and it was completely in spec across the board.

Is there another way to check the MAF for proper working order beyond just the resistance from pin to pin? (Just to be doubly sure. I don't want spend $75-150 on a new MAF and not have it fix the issue) I know also, it could just be an air issue with the engine (vacuum leaks, or IC piping leaks) so I'm getting some starter fluid tomorrow to check around the manifolds and soap-water checking the IC piping.


Also, anyone sure about MAF's being ECU specific? Or do I just need a turbo MAF...

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iTrader: (7)

Yesterday, before rewiring the MAF, I decided I was going to check timing to help rule out possibilities and when I started the engine it started making the awful one-rotor lawn mower noise, with poor idling and vacuum, and vigorous motor shaking.

So I went ahead and checked compression with a piston-engine compression checker:
It was bouncing in the 40's on the rear rotor, and had 115psi overall on all faces.
in the front it was bouncing in the 30's, but only had 90psi overall on all faces.
(from what I understand, front rotor's usually go first on 89+ motors as well)

That sounds like POSSIBLY a bad seal to me, but only based on the differentiation of compression between the two rotors. I was getting three strong swooshes still from the front rotor, but the reading was just lower. I just want to be sure here..
What can cause the motor to only fire on one rotor?

CAS issues, fuel, or timing, correct?
The CAS was in spec, but it could possibly be a wiring issue..so I guess I could go back through harness
I made sure my timing was at stock to make sure that was is not it.
Lastly, I just need to hook up a pressure gauge and double-check fuel.


If it is a blown motor though, I'm trying to figure out what went wrong. It's a low-mileage motor from Japan2LA and I was under light load, driving the car to work one night when it started acting funny in the first place. This spawned me checking into error codes and trying to diagnose my problem. Although, I did not check compression earlier, the engine was generally sounding fine and would increase rpm's at a normal rate until after I got it home. Is it possible to have seals go bad during idling conditions?

j9fd3s

iTrader: (3)

just a turbo AFM. you could check it with voltage while its running too, the FSM gives some specs

i guess, it would be a little unusual though. lets hope your compression gauge is bad or you did the test wrong?

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iTrader: (7)

update: bought new leading plugs, since the old ones looked a little carbon deposited. Both rotors are firing again, but I'm still having the same hesitation issue.
My boost gauge was reading 13-15inHG, so it might possibly be a vacuum issue still.

Does anyone have suggestions as to where to check next?



j9, I did check voltage of the AFM while running and it was in spec around 2.5v as per the fsm (2.5-3.5v), I was just curious if anyone has done a voltage graph in relation to airflow readings on a good working AFM to see if there was anything I could measure mine against.

I also put my stock secondary injectors back in and zero'd out the fuel map for SAFCII, as well as checked the grounds and even beefed up the grounds for sensors circuit. Which did not alleviate the hesitation

I'm going to look for vacuum leaks throughout the system today, and report back. I appreciate you giving me ideas though, anything helps at this point

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iTrader: (7)

I was reading through this thread because his issue seems very similar to mine.

https://www.rx7club.com/showthread.p...itation&page=4

Could the fuel pump resistor relay cause this issue, even though my walboro fuel pump is relayed directly to the battery? By that I mean its giving a bad reading to the ECU, so its causing limp-mode or hesitation?

I measured voltage at the pump today too, just to be sure it wasn't the pump going dead and its reading 12volts. That being said, it could still be a fuel delivery issue... either the injectors, or a clogged filter or something.

EDIT: I'm just trying to narrow down my culprits. It's either fuel delivery, vacuum leaks, or an ignition issue. At this point my money is something fuel related - either an electrical issue regarding the injector wiring (because i'm having the same issues with two different sets of injectors), an incorrect voltage reading at the ECU, or a clogged filter or sock in the tank.

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iTrader: (7)

I feel like a complete idiot. I rechecked the MAP sensor today, and the voltage was low for what it is supposed to be. It was reading 2.2volts at the sensor, and 2.3volts at the ECU WITH JUST IGNITION ON AND AT IDLE.

As per the FSM, it should be at 3.4v-3.6volts at ignition on, and 2.8-3.2v at idle!

So I checked for continuity just to be sure and it only had .6ohms resistance between the connector and the ECU. That sounds like a bad MAP sensor to me.

I'm curious why it wasn't throwing codes for it?

EDIT: I just tested the MAP sensor at 100mg vacuum and it was reading 2.01v which is in spec for the FSM's 1.9-2.1v at 100mg vacuum... It still should be reading a higher voltage at idle and at just ignition on though.

cone_crushr

iTrader: (18)

38 posts for this issue? Dude you need to focus. You're all over the 'map'. Did you get a new VOM or something? You're testing a bunch of sensors that have a low probability of being bad (although you haven't mentioned the IAT sensor yet). Your sensors are fine (hate to say this since I just sold you a MAP sensor) and you're timing, fuel pump resistor (lol), and MOP are OK (unless they're disconnected).

Your problem is most likely 1) a mis-set TPS, perhaps with 2) a vacuum leak also. You need resolve these issues FIRST rather than probing all the other BS. I know it can get frustrating , but it's important to be systematic or rotaries will turn your hair grey.

cone_crushr

iTrader: (18)

As an aside, I think you've revealed an error in the FSM. The ECU terminal table (in Sect F2) shows the following expected voltage readings:

ambient pressure = 3.4-3.6V
100mmHg = 2.8-3.2V

Both of these readings are off by 1V and should be:

ambient pressure = 2.4-2.6V
100mmHg vacuum = 1.8-2.2V (see pressure sensor inspection list for confirmation)

Mazda is very sorry.

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iTrader: (7)

Perhaps you're right. I have been a little all-over the the place because I've never had to diagnose anything that wasn't a carb'd engine. Even though the ambient pressure should be 2.4-2.6v mine is still reading low- is it not?

I went ahead and checked the TPS today to rule it out. I let the engine fully warm up to operating to temperature and then turned the car off and set it to ignition on to check voltage readings.

The narrow-range tps (G/R) was reading 1.2v, so I adjusted it to 1v. The Fullrange (B/R) was reading .8v Both of these readings were double-checked at the ECU as well.

To make sure the TPS was in spec as well I checked for resistance:
Narrow-range (connectors A-B)
closed: 1 kohm
WOT: 5.03 kohm

Full-range (connectors E-D)

closed: 1.06 kohm
WOT: 4.76kohm

Vacuum could possibly still be an issue, I've been using starting fluid around the throttle body, intake manifolds, and injectors and haven't noticed anything out of the ordinary. I need to pressurize the system with a friend this week and use soapy-water to check for leaks just to be 100% sure. Since my vacuum reading is on the low side.

I sent you two PM's Monty, check the second too please. Also as I said in the PM, thanks for the guidance- I could use any and all help at this point.

lastphaseofthis

iTrader: (8)

This is your problem, OMP so what if it doesnt have a code for it yet, it test OUT of SPEC, and it's THE problem with S5's

I thought on it was long ago said, without doubt, that only the omp will cause limp home mode, and other people that think/thought they are in limp mode had other issues.

the only thing that sounds funny is limp mode for me was always right on the money at 3500.

TESTING IF IT"s the OMP
Get going about 20 mph in 2nd, and turn the key off for 2 seconds and then back on, and go WOT..... it will take about 5 seconds before the omp tells the ecu to go into limp mode.

If you can rev past 3500 and go WOT it's the omp... which is OUT of SPEC.

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iTrader: (7)

I put in a good working OMP, that I tested for resistance of both the stepping motor and the position sensor, and my issue is still the same...Actually possibly progressively worse.

With stock injectors and my SAFCII's fuel map set to stock for the ECU, I'm having issues giving it any throttle beyond 5-7%, and I get breakup past 2000rpms. I'm with cone_crushr at the moment, it could easily be a vacuum leak. (or possibly still a fuel or ignition issue) It just started raining here, so I'll have to take a break for a bit. But the next thing I'm going to check is vacuum leaks as he instructed.
I need a more solid process of elimination.

j9fd3s

iTrader: (3)

if you wanna just start over, you'd;

1. check compression. make sure the engine is running ok first, if its flooded it'll fail the compression test.

2. check for vacuum leaks. there is a place that sells an intake pressure tester, but its really simple, its just a plug with an air compressor fitting.

3. reset the TPS, and timing i like to get the engine HOT to set the TPS, and i like the lights, but voltage should work ok. just set timing to stock. i also like to check the plug wires, they need to be under 16K ohms (per meter). the higher the resistance the less energy there is to make it to the spark plugs.

4. check codes.

5. i kind of suspect the AFM, if you had another one to try that would be neat, but i haven't seen the car, so its a guess on my part.

lastphaseofthis

iTrader: (8)

if he's starting over, i would look at fuel before timing, fuel pressure at idle? key on engine off? we're all just guessing..

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iTrader: (7)

Double checking compression is never a bad idea so that will definitely be done. My plan was to check both fuel pressure and vacuum this week. I will go ahead and check the plug wires for resistance as well, since that is something I have not checked yet.

I have made a pressure tester already, its a 3" pvc pipe with a cap on it and an air compressor fitting mounted in the cap that's mounted onto the turbo inlet. So I'm going to pressure the entire engine and IC piping and use soapy-water to check for vacuum leaks.

The TPS was set properly today, and I set the timing earlier to stock as well, after i changed the plugs to be sure there.

I unfortunately do not have another AFM sitting around, nor is there anyone that work on RX-7's in the area, no one that I know of or on the boards that I know of anyway.

I think that starting with eliminating vacuum issues and checking fuel pressure is a very good start to narrowing my causes. But I do appreciate the help, even guesses. I'll report back when I've done the vacuum and fuel pressure checks.

cone_crushr

iTrader: (18)

I agree with lastphaseofthis in that there's a lot of guessing going on. It's the nature of text based diagnostics since the 'mechanic' doesn't know exactly what's important and worth mentioning (if he did - the problem would be solved).

While I like the post above (except for the first sentence, hint - It's NOT your plug wires), your plan (& tool) for pressurizing the intake tract to check for vacuum leaks is good. Kind of surprised that starting fluid didn't reveal anything. Can you post a pic of your engine bay; especially the intake & intercooler.

How's your idle? Is it still hunting after setting the TPS or is that resolved now?

It's hard to deduce if your issue relates to secondaries coming online based on your description. If you're really 'hitting a wall' at ~2000 rpm then e car is barely drivable and the secondaries are a long way from transition. However, you mentioned building boost, which would be impossible if struggling to get beyond 7% throttle position. If you press the throttle very slowly (maintaining vacuum), can you get the engine to rev to 4000 rpm?

lastphaseofthis

iTrader: (8)

Pressurizing the intake Would be the next logical step. i'm betting on air leaks around the injectors+other issues.

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iTrader: (7)

This is an engine bay shot from my photobucket:


Initially, I was able to drive it home if I stayed out of boost. This was when I had 750cc secondary injectors installed. I since had removed the upper intake manifold and installed the stock 550cc secondary injectors. However the issue still persisted when I went back to the stock injectors. I will say that the upper rubber grommets that go around the injectors looked pretty dry-rotted so I'm going to replace those this week as well, while checking for vacuum leaks.

The idle however does not hunt anymore, or surge, it just bogs if i punch the throttle or try to rev up past 2000rpms at this point. It does fluctuate though, which is also another symptom of vacuum leaks.

Since taking off the upper intake manifold the hesitation has been at a lower rpm, making me think regardless of what the INITIAL issue was, I have vacuum leaks on top of that. After making sure that the TPS was set to the proper voltages today, I still could not rev it past 2000rpm's even while maintaining vacuum. Which leads me to believe vacuum leaks are a definite possibility and probably likely from me removing the upper intake manifold- electronics issues aside.

I don't have a closer picture of the intake and manifold at the moment, but I will take some and post them tomorrow while checking for vacuum leaks.

My intercooler is an Isuzu NPR intercooler:

And my couplers are 4-ply braided. It could be a vacuum issue there, but I feel its more likely in the manifolds or around the injectors as I stated before...However that's why I am going to pressurize the whole system, to eliminate any vacuum leaks. I'm glad on the right track, I appreciate the input guys.

cone_crushr

iTrader: (18)

Excellent engine bay pic. I'm concerned about distracting you (lol) from the real issue, but here are a few observations:

1) Overall a decent install and a killer FB.
2) That's a hose clamp farm; I count 19! You definitely should pressurize the system and make some bubbles.
3) Hmm, a stock FC fuel filter where I would expect to see an aftermarket fuel pressure regulator. FYI, The stock S5 rail mounted FPR is marginal once you start turning up the boost past 12 psi.
4) Not a fan of the foam shroom air cleaner, but it's probably benign as long as theres a structure to prevent the foam from collapsing.
5) Odd place to mount the AST (by the hot turbo) and suspicious of those hoses.
6) Can't see your IAT sensor. Is it in the compression tube?
7) No need for power steering on a FB you lucky dog.
8) You desperately need an aftermarket ECU.
9) Stock oil cooler lines kinda risky depending on age.

Enuff for now. Don't worry, you'll be smoking tires soon.