hey i have a 91 NA. if you apply excessive throttle, it'll die out (sounds like its choking) or bog like crazy. if you apply moderate throttle, it's fine. problem occurs at idle as well as under load. has a CEL (dunno what it is yet cuz i dont know how to pull it) and the exhaust coming out from the back is extremely hot. it feels like the gas is just flowing from the exhaust (you cant feel the gas push against your hand when you put it next to the exhaust). I've already replaced all the plugs and plug wires and did an oil change.

 

Umm, clogged cat, maybe?

Also thinking clogged pump filter or main filter, although that usually doesn't manifest itself in idle...

 

I was thinking that as well, but I unbolted the exhaust from the downpipe, which shouldve freed up some backpressure but it didn't work; still bogged. How do you pull a CEL?

 

Under the hood and behind the drivers side headlight there are two green colored connectors that are not connected to anything. Take the one with only one wire going into it and ground that wire to the frame.

Turn the ignition to accessory and start counting the flashes of the CEL. Long flashes are 10's and short flashes are 1's. There is 1.6 seconds between each code read. So LONG-LONG would be CODE 20. LONG-SHORT-SHORT-SHORT-SHORT-SHORT would be CODE 15. Match the code up to the table of codes found in the Fuel section of the FSM. My guess is that it is an MOP problem of some sort.

How do I know, I am tracking down my own MOP issue. BTW the symptoms you describe are identical to mine. Start premixing immediately to save future problems. Even if you premix forever, as far as I have been able to tell, there is no way to bypass the MOP signals to avoid the "LIMP HOME" mode you are currently experiencing.

 

^ dealing with a broken mop is a friggin nightmare. in my case i had to replace the mop and ECU b/c they were both fried...luckily i only had to pay 30 bucks for a jdm mop off ebay but the ecu set me back 350 from a local mazda shop. before you replace them, check the ecu b/c if it is fried and you put on a new mop then the new mop gets fried and if you put a new ecu with a broken mop the ecu gets fried...it is by far my biggest complaint towards mazda about fc's other than i wish all fc's were turbo...limp home mode sucks when your 180 miles from home and have to take the interstate...man just thinking about it gets me all fired up.

 

whats MOP?

 

nm figured out what a MOP is. also there's a lot of oil leaking from this jumble of hoses and stuff near the rack/pinion and sway bar near on the passenger side.

 

where's the MOP located?

 

It sounds exactly like the ECU is putting the car in fail safe or "limp mode" as jeff48 described already.

The place you detailed that had oil leaking is the MOP. You should really resolve this issue as soon as possible. The MOP could need replacing and the ECU will need to be checked to see if it is fried.

And while it is likely the MOP putting the car into fail safe, check the throttle sensor as well. Mine was completely stuck and the car went into fail safe mode. It was much more pleasant of a fix than an MOP/ECU combo.

The MOP has four hoses coming from it on the front passenger side of the engine.

 

Yeah the TPS was one of the first things i checked. Guess I gotta buy a new MOP. At least I dont have to buy a new ECU...my friend is in the process of doing a TII swap in his car. Could I use an ECU from an 89 vert?

 

the tps is not cheap either (cheapest new i found was 296 shipped). i was in the same postion you are in .. after buying a tps ( slaps myself) i was farting around under the hood and grounded the computer terminal and i started getting a flashing on my idiot gauges. well the previous owner swapped a s4 set of gauges with the s5 ones. so i had no check engine light .. i had a constant "belt" light. well after seeing the flashes i figuired out that i needed a omp or MOP . normally with the mop the computer gets fried as well. but i lucked out and only the sensor was bad. and all i needed was the pump and the ecu i bought was not needed. if you need a new ecu i have a "350" computer .. you just need to locate a s5 omp . but pull the codes . if you get a 26 or 27 i think .. swap out the omp.

 

is it a good idea to change the hoses as well? looks like the previous owner before me knew the OMP was out and changed some of the lines...some of the hard lines are replaced with rubber/plastic lines and secured with duct tape. lol. there's no way into tricking the ECU into thinking the OMP is working and just pre-mixing?

 

actually there is.. a few ppl with S5's have done it wouldn't know how to do it myself since i own an S4 and for the moment still retain the stock MOP

Frank

 

hmm...here's the status. pulled the codes and this is what I got:

9- Water Thermosensor fixed @ 176F
12-TPS Full Range
18-TPS Narrow Range
27-MOP
37-MOP

Well the TPS I disconnected a while back (whoops) just to see how it would run...I guess thats what triggered the MIL. Hopefully the ECU is still okay. Anyone know how to run premix on S5 without making the car go into limp?

 

I would just get a new MOP.

 

<-- cheap

 

comments anyone?

 

I think I'm in this same boat right now too....

Codes 20 ad 27

Where's the MOP at and where do I buy a new one at. Also, if the 89 vert ECU doesnt work for project7, PM me, thats what I have and may need to buy it from you.

 

if you need a good mechanic, mr mazda in campbell is all knowing about fc's