ChrisJSheridan

Good afternoon everyone -
So I have had trouble with my s5 vert. I have replaced the TPS myself twice. I just paid Mazda for a new one plus install and adjustment. I have no check engine codes. I have had this car almost a year now and half of it's time has been garaged because of whatever is going on.

Today - same story as it has been. cruising on highway and I get fuel cut. Shut it down and able to restart, get back on it. Fuel cut. Big backfires, lots of smoke. Brand new TPS not even a week old. I am getting ready to check if they installed and adjusted it to spec, but if it's all in spec. what else could I be looking at?

Also -
I had a compression check done. I am still in spec but at the very bottom end.

Here are things I have done that may or may not effect the issue:
Water temp sensor
TPS 3 times
oil changes on time
s6 alt upgrade
Mazdacomp mounts
Lead ignitor
spark plugs

I'm tired of chasing down issues, I just need a break here.
Last bit of info, might be related or completely different. My tach quite working this morning, after 10 minutes it kicked right back in???

Can someone help me out here?

Thanks in advance!

Chris

ChrisJSheridan

And air pump has been removed. Not sure if that makes any kind of difference or not. I would assume all ports have been left open

diabolical1

iTrader: (3)

have you pulled any codes?

you sure you're not going into limp mode? have you checked your MOP?

ChrisJSheridan

No codes were generated.
What's the mop, I am at work now and can't look up the acronym

pzr2

iTrader: (3)

MOP, OMP, same thing, it's the little tumor off the front cover that squirts oil into your engine and keeps things lubricated

eage8

iTrader: (9)

MOP = OMP = oil metering pump.

They have a tendency to fry ECUs when they die.

diabolical1

iTrader: (3)

MOP = OMP = metering oil pump/oil metering pump (depending on who you're speaking to)

read post 3 in this thread and see if this is what you're experiencing:

https://www.rx7club.com/2nd-generati...e-mode-926212/

i just thought this was an interesting thread because i did not know that the MOP usually takes out the ECU when it craps out.

https://www.rx7club.com/2nd-generati...p-mode-950899/

ChrisJSheridan

-wow that 3rd posting really kinda hit the spot. So I could possibly be looking at a fried ECU now too?

ChrisJSheridan

alright now that I've taken a nap and ate lunch, had a chance to level off. How do I check the MOP? Mazda deal just spat out $2300 for a new one. Mazdatrix told me $1600. anywhere else I should check? I have had extremely bad luck with anything used on this car

satch

iTrader: (1)

If you open the ECU you could look over the circuit board for any signs of obvious damage.

Have you unplugged a sensor such as the boost sensor to see if it would throw a code to see if the error code aspect of the car was perhaps operating properly?

A used OMP and ECU are rather common parts found in the for sale section.

OMP testing procedure thread:

https://www.rx7club.com/2nd-generati...2/#post7628548

ChrisJSheridan

Well -
Since I need a quick turn around on this. I sent the old girl back to Mazda for trouble shooting. Besides, the work they did is warrantied :0). If I had time on my side I would have gave the OMP / ECU testing a whirl. I sure hope it's work they did!

ChrisJSheridan

I got it back last night. Mazda said they couldn't duplicate the problem and sent her home. She made our home fine. To work fine. Back to work on my lunch. .. fail!
I did manage to record a little bit of what's going on

https://youtu.be/3D-lqlcssX0

satch

iTrader: (1)

If you have a problem w/the OMP then driving the car is not going to help. Again, you can test the check engine light as that would provide some insight. Also, giving the ECU a look over would also help to determine what's going on, as well as testing the OMP.

ChrisJSheridan

Based on the video, is this truly going into limp mode? Description is good but a visual confirmation can be valued too

satch

iTrader: (1)

A car which goes into limp mode can also come out of limp mode as it just depends on the situation. When it's in limp mode you will know it.

gxl90rx7

iTrader: (1)

it didnt go into limp mode in the video, but not saying it didnt go into limp mode when you say your tach stopped working.. the tach does not work in limp mode and you wouldnt be able to rev over 3500, which sounds like your original symptoms. only two things cause limp mode, a faulty OMP or a failed AFM

the AFM directly affects fuel delivery and could cause your problems, and is easier to get to, i would swap that out with a known working unit to see if it clears the problem

if it does end up being a bad OMP, i would remove/block it (you will have to premix), and get the RTEK ecu upgrade, which disables the OMP fault

Hot_Dog

Check your AFM. There's a temperature sensor (i.e., resistor) that might be bad. I am the original owner of a 90 GXL with 320k miles. When my car was new, I had a similar problem where the engine would suddenly cut-off while I was driving. Took it back to the dealer, and after a week they found that the AFM was bad. They replaced it under warranty and I've had no problems since.

tk49

limp mode can also be triggered by TPS, car will rev over 3500, just limited to 20% throttle opening, I am fighting similar problem, only code 12,18

j9fd3s

iTrader: (3)

just looking at the video, it looks like it intermittently doesn't idle? and maybe not drive, but then magically goes away and is fine?

just based on that, i would do the following.

1. pull codes, there are some that do not turn on the light.
2. if you have no codes, then it is something mechanical, so i would see if i could beg/borrow/buy a known good afm.
2a. have a look at the fuel pump
2b. look at the ECU and make sure its not wet.
3. you need to get serious. you need to let it run and wait for it to act up, and be ready to test stuff when it starts acting weird. might take a while. may speed it up to wiggle/tap things in the engine bay.
3a at least you know its not the tps, or the coolant temp sensor. the tach works, so its unlikely to be the ignition.

RockLobster

iTrader: (7)

I'd just order a used, known good, ECU and try it. Have you tried a different ECU?

I'd suspect ECU simply because the randomness of it all. Also the fact that your tach quit working for a while.

Low compression could cause what you are experiencing as well (except the tack cutout makes me think otherwise).

WhatsAWankel86

This is close to my issue!! its about as intermittent as yours and i get black smoke like a mother, but mine doesnt straight up die. itll sound like a big block chevy for a bit white is pours out smoke and back fires for a while, also changed tps , removed air pump. just realized today though that my oil metering lines are all melted.....

WhatsAWankel86

i just checked for codes again tho and i got AFm .. so ill m=be ordering that hopefully it solves my issue

ChrisJSheridan

well its been a while since I was last on here. Here is my lesson learn. Trust no one elses work!
I went back through everything. and when I was ready to park it in my garage. I started it up, warmed up, shut down and then checked the work mazda did with the tps. I adjusted the TPS. Drove all May. discovered that the lock nut was walking on me and called for minor adjustments every so often.

Well now we are into June. And the problems started again. I have done pretty good keeping a multimeter with me at all times. This time when it died and checked the TPS adjustment, I couldn't register any voltage to it while the motor was warm. I had it towed home ( the driver knew the car before he showed.... story of my life!). I haven't had a chance to check it again yet. What is the flow of power to / from TPS? could it be something else in line? Could have I fried a brand new TPS some how (voltage has read normal)? Is there a bi-metal protector inline some place as the car warms up?

Thanks in advance!

Chris

j9fd3s

iTrader: (3)

i suggest reading the manual, you'd be way ahead by now, Foxed.ca - Mazda RX-7 Manuals

there isn't a bi-metal protector, but there is a wax pellet that kind of does the same thing. the wax pellet physically pushes the throttle open when the car is cold, which is what gives you the ~1600rpm idle. when the wax pellet is ON, the throttle is open.

the TPS adjustment indexes the ACTUAL throttle position with the ECU's throttle position, when the TPS is correct they both agree.

if the TPS is adjusted with the car cold, the throttle is pushed open by the wax pellet, so it is not at zero, but you're trying to tell the ECU its at zero, so it will be off. get the car HOT and adjust the TPS.

every TPS works the same, there is a 5v input and a ground, and then the 3rd wire is the signal, which is a 0-5v. the S5 Rx7 is a bit unique in that it has TWO tps sensors on the one bracket, however they are both normal sensors. one does the whole 0-100% throttle sweep, and the other does 0-33%, at a higher resolution.