I have this problem with my '94 f150 (300-6, 5-speed 78,000mi), and it's about driving me insane. Every few shifts into 3rd gear the engine doesn't rev down when I push in the clutch so when I shift it grabs it into gear and GRINDS really harsh. Even if I shift really slow, which I have been doing since this problem has been happening.

Is it my clutch? Is it not engauging and needs adjustment?

I was giving a Airaid throttle body spacer and I installed it. I couldn't tell much difference in performance but I wonder if that has something to do with the not motor revving down when I go to shift?

What do you guys think?

 

Sounds like you have at least two things going on.

The engine not revving down when you take your foot off the gas is probably the TPS. Easy to test and replace if it's bad. Do a search for more info about it.

Even if the revs don't match up, the tranny shouldn't grind. Your synchros might be worn, or it might be as simple as needing a tranny fluid change. There are three rubber plugs on top of the Mazda tranny, and they tend to dry up and then leak. I would drain the tranny and refill with a good synthetic ATF Mercon III.

 

Hey AndyM, I changed my tranny fluid at 62,000 with just cheapo stuff, Mercon III can't remember what brand though. Is Synthetic worth it for my tranny? I'll try and find some stuff on the TPS as you say. Like I said, it's happens about every 5th 3rd gear shift or so. Although, it does seem to do it when I floor it then shift at about 3000rpm... almost everytime.

Would that throttle body spacer have anything to do with it? Do you think it has anything to do with the clutch?

 

It might. Did it do it before you installed it? If not, then I would suspect that's the cause.

Synthetic is definately worth it for that tranny. It's a couple bucks more, but you'll notice a big difference in shifting.

 

Last night I was reading up on the TPS on here... seems that many people are having problems with high idle, which isn't quite what is going on with mine but might be related.

I can't really say that this problem has been occuring since I put that spacer on there. But it could be a cause. From what I read last night I need to:

- check my TPS with a meter and if bad buy one for around $30

- check for anything hitting my throttle return spring (maybe that spacer is causing something to hit the spring and not let it go back)
-check/ clean my IAC
- disconnect battery and clear anything out (might not be a bad idea?)

If I change tranny fluid I probably will go with synthetic. Hopefully I found out what's the freakin' matter soon.

 

ok guys, I need some more help here!

I cleaned my IAC valve, EGR valve, and TPS, and throttle body all with carb cleaner until spotless. None of them fixing my problem. My IAC was pretty dirty but nothing too bad. I checked my TPS with a meter as stated in this thread: https://www.ford-trucks.com/forums/s...d.php?t=209780. It was all within spec and moved slowly no major jumping around.

I checked all of my vaccum hoses. I checked/filled my tranny fluid, only half a quart low. I was looking at synthetic tranny fluid and Mobil 1 is $5 a quart! That's $35 in tranny fluid, whoa.

I checked my linkage, no hang ups that could cause hangups. No check engine light on, nothing. This is the silent hunter! My motor is not revving down fast enough like it should for me to shift, (even if I shift slow and wait 2-3 secs before switching gears -with the clutch in- it still won't go down) I can watch my rpms stay the same or SLOWLY drop. Which makes me believe it's something motor/vaccum related.

Just for info sake, my 5-speed tranny is a F1TA-GC 8634180. Is that that Mazda POS?

My TPS is a F2TF-98989. When I went to Autozone they had 3 different ones listed for my truck and they had to know for sure which one I had.

So, what do you guys think??? I'm totally stumped...

 

Do the rpm's hang at every shift, or just 3rd? If it is just 3rd, then I'd think that the synchros might be worn on 3rd. Check under the dash to make sure the clutch pedal is getting full throw. It should be on the rubber stop when it is all the way out. There is a bushing connecting the cross shaft lever to the pushrod of the clutch master cylinder that can wear out and cause you to not get full disengagement of the clutch. There are also 2 or 3 other bushings on the cross shaft where the brake pedal rides on the cross shaft and where the cross shaft goes through the pedal bracket that can be worn, causing misalignment and also not allowing full disengagement. If this is happening, it's more likely to be apparant when clutching to put in gear after idling in neutral with the clutch out. If you double clutch (in gear, clutch, shift to neutral, release clutch, depress clutch, shift into gear, release clutch), does it still grind?

what is the TPS voltage at closed throttle? It should be less than 1 volt. How erratic is the voltage increase? It should be very smooth and linear - shouldn't jump at all. However, if it idles well, the jumpiness would only be apparant when you are in that jumpy region of the throttle position and should be ok when you drop throttle all the way closed.

 

EPN, wow so many questions and so many things to check! Awesome.

The RPM's hang on shifts 3rd and 4th only sometimes. This problem isn't an every shift thing. I think my 3rd gear syncros are worn because of this problem. I've ground 3rd gear so many times I wouldn't doubt if the teeth are gone. Whatever is problem is, is ruining my tranny.

My clutch is tight against the stop when it is fully out. And seems to let out fine, maybe 1/3 from the floor, normal I guess.

I think it's in my TPS. When I tested it, my numbers didn't quite match yours. It was like 4.6vs your 4.8 and open was like 1.8 or so. I even tried two different meters and the results were only 1,000th off of each other.

I haven't tried double clutching it but it's hard to know when it's going to mess up. Like I said, it's about one every 5 shifts or so, maybe more maybe less. I haven't been able to find out what makes it do it more or less.

1st and second seems to always go fine, no hang ups and good throttle let-off response. But 3rd, and 4th seem to be trouble. 3rd being the worst...

 

Also, if you haven't done so already, check the fluid level in the clutch master cylinder. I guess it could be the TPS since it is an erratic problem, but it is odd that the rpms only hang between 3rd and 4th.

 

I've checked the fliud in the clutch, it was low, but nothing normal - topped it off.

My 5-speed tranny is a F1TA-GC 8634180. Is that that Mazda POS?

I went to autozone and they had to special order my TPS.. they had 3 different ones pop up on the computer. It'll be in Friday, I have a feeling it might be the problem.

 

You have the Mazda transmission - M5OD.

 

kinda sounds like your throwing the synthetic idea to the side just so u know in the long run its a good idea not only because its slipperier but, we had a topic about fuel mileage earlier and most people were getting about 15 mpg on the straight 6 forum except a coupel guys we kept annoying them try to figure out what they did different than us gear trannys engine mods what not we found out after much debate the only difference was putting synthetic in engine,tranny. and both diffs and the mileage increase was quite good he had 24 mpg compares to our 15 might be a good idea befor u shun the extra few bucks to the side by going with castrol like i did

 

Gerry, I got disapointed when I saw the $4.99 a qt. price but I'm open to it. What brand is recommended to use?

What do you guys use to put the tranny fluid into the tranny with? Last time I did it, I had to use a big oil syringe and it took forever at only 6oz per shot!!

I'm only getting 13.9 in mine but I give long warm ups in the early mornings, average 45min per week.

My problem seems to actually be a little bit better since I cleaned my IAC, TPS, and EGR.... but still not totally gone. My new TPS comes in Friday, on the computer it came up as 'fast throttle response' as a side note within the part number... hrmm.

 

Update Jan 1st: I put the new TPS on there and no help. It actually lopes my idle - at idle. Also, poor fit. It doesn't seal near as tight as the OEM. So I put the OEM TPS back on there. I took off my Airraid spacer plate, and put it back to stock. No help either. What else is left to do? My tranny has grinded so much I might as well change the fluid. While I'm at it I guess I should put in Synthetic, as advised in previous posts. Any ideas on Full synthetic or just aditives synthetic?

Different question.... Is there any adjustment in the throttle cable?

 

Did you check the voltages with the new TPS? You might also need to unplug the battery for a few minutes to force the computer to re-learn the operating parameters. The orange wire should have a steady 5V with the key on, and the green wire should have less than 1V at closed throttle. I would also check to make sure all the ground wires are clean and making a solid connection. Bad grounds can cause a lot of strange problems. I don't think there is any adjustment on the throttle cable.