hey guys, just got done making an account. i have a 94 fd auto with the twins. and i am having my first of many problems to come im sure. i live in kansas city kansas and i work in olathe kansas (about 25 mile drive) the other day i was driving the fd and it cut out at about 4k then shifted... its like its shutting itself down or something. question is... does anyone know a good place to take it to have it looked at? im not lookin to spend a lot of money on it but i also don't want it running like crap.

 

You are about out of luck if you are looking for a shop in this area. This is not the car to own in the KC area if you don't have the tools or time to get dirty. When you have access to send Personal Messages here on the forum, send a PM to "RTS3GEN". He used to do a lot of work on these cars for local guys at very good rates (he's in Lees Summit). I know he's busy with his own current project but he may be able to make room in his immaculate garage for another FD to work on.

 

As cars go this isn't a great car to own on a budget. Especially if you need to drive it.

Is it cutting out when you're on the throttle? What speed?

Does the car have any mods? What are your mechanic skills?

 

well i bought the car with aftermarket intake pipes and a high flow down pipe. and it looks as tho they took out the turbo synchronizer. as for my skills... i am a very experienced mechanic on import cars. i can do just about anything that is needed, i just know nothing about a rotary motor. i understand the concept and the internal workings, but it still seems like they run on hopes and dreams to me. i dont have to drive this car every day, i do have 2 other cars but i love how the 7 handles and the power and everything i relly wana get it back on the road.

im sure i can handle working on it, i just need some guidance. has anyone had this problem before?
when i am full throttle in any gear it acts like a fuel cut at 4000 rpm. (stalls and comes back) but if i reduce throttle to about 50% then the car pulls good and boost is good... it acts like a rx7 under 50% throttle. its just full throttle that is killing it. any ideas?

 

Start here:
http://www.autosportracetech.com/RX-...leshooting.htm

 

Start by installing a boost gauge. If you've seen discussions of "10-8-10" psi boost pattern, that's what you're looking for. It's quite possible that 4000rpm is your secondary turbo transition and it's overboosting and bringing in fuel cut. In that case the boost might be 10-8-12-10 where the 12psi hits very briefly at 4k.

If that's what it is then a boost controller should solve the problem.

David

 

very helpfull info, thanks to both of you. it is a very probable cause. i do have a boost guage in the car, yet i dont know how accurate it is. looks old and was in the car when i bought it. just to cover another problem...
the reason i think the turbo sync is out is cause the exhaust vacuum valve looks to be removed and replaced with a bolt. should i track down an other vacuum valve and install it before trying the boost side, or just make sure the boost side is working properly?

 

What I would recommend is getting your bearings first.. By that, I mean start with a functioning boost gauge. Verify the one you have is or isn't working. If it's working, start with getting your vacuum reading at idle and what your idle rpm is... If your boost gauge is working, this will help determine if you have a vacuum leak or not.

After that, start with the boost test:
http://www.fd3s.net/boost_test.html

Based on your results there, we can help you with the next steps.

 

awesome. will update when all is checked

 

ok just got done going through all the rats nest of hoses with a factory diagram... all hoses are replaced, running to the correct location and secured.
boost gauge is more accurate than i thought, but a little off on vacuum, so another gauge was used for the testing (brand new test gauge)
base idle is 726 (on my snap-on scanner when tested)
vacuum has a slight bounce on the needle between 9inhg and 9.5inhg

boost on the other hand never gets above 8psi at full throttle, at 3/4 throttle it gets to about 11psi.

as i mentioned earlier, the turbo control actuator was removed and the butterfly plate for the charge control actuator was removed. i have the hoses running to the charge actuator and the lines to the turbo control now plugged.

thinking that the vacuum test seemed low i did a smoke test on the intake with no leaks found.

and now i am stumped and turning to the rotary gurus. please help if you can.

 

i think i may have just found the issue, while test driving just a moment ago i blew the lower intercooler hose off and when i went to reinstall it i found a temp sensor broke off the front of the thrmostat housing. am gona install a new one, after calling mazda on it tomorrow.

will update

 

ok temp sensor didn't make any difference. im out of ideas.

 

Ok, let's back up and see if we can make sure what's happening:



When you accelerate at full throttle, the car cuts out around 4000 rpms; is this correct?

What is the boost level when this happens?

Has this happened the entire time you've owned the car or did it just start all of a sudden?



If you are free next weekend, I should be around a little if you want to bring the car by to take a look at it..

 

yes, at full throttle it cuts at 4k rpm. im not sure if its done it the whole time, i never full throttled it till the other day. when the engine cuts out its only at 7-8psi. i have repaired all the vacuum/boost leaks, as far as i know. and now all the sensors are working properly as per my knowledge.

 

If you are willing to bring the car by, you can take me for a quick ride to feel what's happening. It's hard to tell you what to do as I can't tell if you are having a hesitation or if the car is basically being retarded like it's hitting fuel cut.

 

ok, i took the car out again today, i believe it is hitting fuel and/or ignition cut. i was wrong, it doesn't cut at an rpm, it cuts at 8 psi no matter what rpm im at. but i thought these cars had like 10psi factory?

 

Fuel cut shouldn't happen unless you are getting above 10 PSI (depending on the boost level and/or rpm). Have you checked to make sure you don't have any stored ECU codes? I'd be curious to see if maybe something is retarding the car (possibly knock sensor).