94 RS D6-DE F25M-R High or creeping idle

[specialtyneed]

The Man trans also does not want to go into reverse but its likely due to high idle if I get RPM down by going into 2nd and letting out clutch some and hit R fast before she creeps up in RPM it shifts good into R. I also have to downshift into 1st early while still moving pretty fast or it does not want to go into 1st.

I have a high idle problem with the '94 RS have adjusted it down w/ air screw twice but it seems to be increased by the computer &/or the idle switches to about 1600 rpm and causes drive-ability shifting problems likely due to idle speed throwing off the syncros with the trans. Anyone know what is happening here? Have not had time to troubleshoot idle yet. Otherwise she drives great. Trans really likes a fast clutch action and fast early shifting if you are lazy or hang and work clutch slow it wants to miss gears and have to double clutch like syncros get out of time.

[Ryan]

Reverse is not synchronized, its perfectly normal that it doesn't want to go in sometimes.

The method I've been using lately is to pop it in 3rd and then into reverse. Seems to work perfectly. MrMazda was the one to teach me that, I think...



When you adjust the idle screw you MUST be in Diagnostic mode (Jump TEN and GND in the DIAGNOSIS box)

To start, turn it all the way in (should kill the car) and then three full turns out. That is approximately factory. Go from there, adjusting the timing to 10º BTDC as you go.

Normally idle issues are #1 vacuum leak, and #2 coolant temperature sensor issues.

[specialtyneed]

Ryan,
Nice to know about the reverse quirk not being isolated to my car or my driving. My wife will be relieved and be less critical. I have seen other man trans be this way just not this bad.

Yes, we have done some looking for vacuum leaks and have fixed one disintegrated small oval plastic filter (seemed to be there for no other purpose than to be calibrated vacuum leak with grey poly foam filter in the pass side plenum several weeks ago. I was aware of the idle diagnostic mode requirement but was experimenting the last two times. I had no problems with idle speed the initial time I set the timing after disty mod however the timing marks were hard to see and make sure I was using the correct one due to how far they are down in there with obstructions. I really wrestled with this timing setting and by the way she runs can not say by any symptom if the timing is off spec.

On the temp sensor I do not know whats normal temp gauge deflection ranges for this car. The dash temp gauge seems to run somewhat low compared to most of my other many vehicles. is there a different sensor from the one the dash gauge uses that runs the computer uses for coolant temp?

Thanks much for the idle initial setting procedure will do in next 24 hrs. How that works out will flush out any other vacuum leak problems I may have. Will do another inspection and do a hydrocarbon spray type leak check. We finally got a break in the 100's+ here. Got to 118 f here in Tulsa area last month and all time record hot August.

Thank you so much again.
Shaun & Laura, Caleb, Aaron, Timothy & Hannah

[Ryan]

I'd like a pic of this metered vac leak thing you speak of... I have a feeling it is the VICS vacuum chamber.

The dash gauge is independent of the gauge the ECM uses to control functions. The dash gauge is the single wire sender, the ECM's gauge is a two pin green sensor, and the fan switch, if you have one, is exactly like the green sensor, just black.

There are specs in the online manuals in the F2 section for testing the coolant sensor. You need means to boil a pot of water, a thermometer, and a multimeter.

For the timing, put a dab of white-out on the crank pulley on the appropriate mark. The flash of a timing light works really well against it.

[specialtyneed]

It was really late at night and very dark and I was extremely tired at the end of the disty mod when I set the timing so did not have time to mark it. Yes great tip on the timing mark. I did the white out or white appliance epoxy paint on the '96 Nissan Quest another one hard to see and get at years ago and it worked awesome.

Got that bout the sensors. Thank You

However that VICS device would be the smallest one I have ever seen (which I think I saw more than one of on the plenum) at about the size of the top or end digit of my pinky finger, maybe the one next to it.
The VG30E Nissan engine (only other engine I have with this type of resonance tech that I have had to dabble with) uses two much larger plastic ones about the size of a large plantain or over grown banana with more round ends but they are attached to the intake snorkel and the air box.

The small device on MX-3 was black plastic male top piece where vacuum tube attached with tang slots to retain it with thick rubber gasket below w/ one large hole in center and two tiny holes in the center area for air to be drawn in to match the plastic top and gray foam in the bottom. Bottom is squarish with ovalized overall shape rectangle. The top the rubber gasket and foam all disintegrated. It was really hard to repair it and keep most of its intended function intact. I used aircraft grade polysulfamide sealant known as PR 890 B2 aka Proseal with 2 hour working life similar to a urethane that uses humidity or water to cure. Sealants in this class are integral fuel tank rated. See about a pic when I get up Monday if that description is not good enough but my digital camera is not good with very small objects.

[specialtyneed]

Got this problem solved. It was exhibiting cold engine froggy (wants to gun best with a heavy gas foot) symptoms even after a good throttle body cleaning like when you remove the thermostat on engines that perform well street strip racing so I had the boys change the thermostat and sure enough the centering pin clip was gone and the pin was stuck in the valve holding her wide open causing me all the rich /high idle dying easy at idle when using very little gas and drive ability problems. I went with a 5 degree warmer stat and I rally like it. MPG is at 29 in the city currently. Can not complain.

Thanks all for the help.

[stepchyld]

Good to hear you got her fixed.

I've found reverse a tricky gear for several vehicles, not just Mazdas. My trick is, if shifter doesn't slide easily into reverse, hold shifter toward reverse with just a little pressure, and slowly release the clutch pedal. Most of the time, the cars I've done this on just slide easily into reverse with just a little pressure, when clutch pedal is just an inch or two from the floor. Takes a little practice sometimes, to not accidentally release clutch too much and grind the gear (I hate when that happens!).

I was around Tulsa a lot last summer, well, from July to October, very hot summer!

[specialtyneed]

Put the high and creeping idle when engine cold with also a when engine warm very low idle particularly bad after heating up during errand short trip restarts to bed. It seems leaks or working off of the connection at the aging dry rotting intake snorkel / bellows bottom line connection and in the convoultions of the intake air bellows cracks between air filter & sensor and intake plenum throttle along with the plenum getting carboned up or fuel fouled at the throttle plate is common frequent issue with mine as she seems to run a bit rich. The throttle will eventually get sticky if let go dirty with buildup too long. Some OEM or Ultra Grey is temporary fix for bellows & line. This is the only vehicle I have ever had a throttle area that had to be cleaned out so frequently.