Serious stutter from stock 95. *GREMLIN*

Hello everyone, I'm happy to find a place with such a huge amount of knowledge.
I've been having a serious problem with my truck for a couple of months now. It's a stock 95 DX 2WD with the 2.4 liter 4 cylinder. I have 277k miles on it and although most of those miles are highway, I have to admit I've driven it hard for the ten years I've owned it. Up til now I've been able to fix everything myself. No mechanics.

Bear with me, there's a lot of history and clues here.

A couple months ago the truck began giving me issues. It wouldn't run higher than about 2k rpm, then it would get better on it's own after some time. I replaced the TPS sensor as I'd done once before but this time it didn't solve the problem. After being nearly useless on the road I took it to my local dealer for a diagnostic. The dealer adjusted the TPS sensor and told me it was driveable. I only made it a few blocks before I was unable to make it up a hill. I brought it back and demanded that they finish the diagnostic they began. After another 3 days in the shop they told me that the noise from the fuel injector rail telescoped down the fuel line and disrupted the knock sensor on the back of the engine, thereby retarding the timing incorrectly. The physical cause of this mixup I'm told, was the aftermarket fuel filter I put on 8 years ago. I told them to replace the filter if that was really the issue. They declined.
What they did do before they came up with the B.S. diagnosis was test the fuel pump and ignition system. Everything passed. I couldn't really argue, because it did run at about 90%. I no longer have any faith in my dealer.

A day or two later the problem came back fully and there are a few distinct symptoms:
1) Inconsistent idle. It will idle at normal rpm and drop sharply for a moment. Sometimes it's enough to kill the engine, but most of the time it bounces back. Usually it drops to about 250 rpm.
2) While driving at any speed, the engine will stutter hard for a moment then regain normal rpm. Similar to the idle issue.
3) Every three or four weeks I will have a major episode. I'll be driving and the power will fade fast. I can't keep speed, I can't get out of the way of traffic and I have to pull over. If I floor the pedal, I can move, but no other position will maintain speed.Strangely, the idle will be perfectly fine. Eventually, after minutes or hours the episode will pass and I can resume driving.
4) At no time in any circumstance or episode has the computer given a code. The light is not out, when I replaced the TPS sensor, I forgot to plug it in before starting and I immediately got a check engine light. The dealer reset it, and I haven't seen one since.

Now, what I've done:
1) Spark plug wires. No change. The old ones were only a couple years old.
2) New cap and rotor. Also unnecessary, but worth a try.
3) New ignitor. It ran smoother, but no change in symptoms.
4) Used distributor. Again, smoother, but no change in symptoms.
5) Used ECU. (I started to suspect that no codes must have meant that the code giving piece was bad) Runs better, but no change in symptom severity or frequency.
6) Two different fuel treatments, first Heet for possible water in fuel, then Lucas for injectors. Absolutely no difference. Filling the tank has no effect on the symptoms.

I don't know what to do anymore. I suspect that the problem is electronic based on the "feel" of the symptoms. Sharp, inconsistent/random cutouts from the engine. I've done my best to keep track of the conditions under which these symptoms occur. I can't find any commonality to them. Hot, cold, wet, dry, turns, bumps, hills, time, engine cold, engine warm, length of trip, loaded or unloaded. I believe that there may be more than one issue here, but I can't think of what they might be and why I haven't been able to solve at least one of them yet.
Has anyone else seen anything like this? My truck must have at least 75k more miles in it if I can just solve this crap. Thanks.

 

Has the timing chain(or belt) been replaced-At how many miles? Tensioner pulley and associated parts?
my four banger RATTLED at startup-you could hear the chain. I replaced it immediately--do know what symptoms would have developed.
At 277k mi. HMMM.
Keep us posted.
Seems like you have replaced many things already.
What engine # 22r.
TIMING ?????????????

 

Thanks Nate, I'll check out the IAC. The first thing I replaced when this problem began was the TPS with no change, and I don't have any noise issues. I've never replaced the timing chain and I probably should. I have to imagine that if it was skipping teeth, it wouldn't revert back to running well. Usually a skipping chain will only go one way.

 

Sounds like an EGR Valve to me. And if you've never changed the 02 sensor....at 277,000 miles it owes you nothing.

 

That's a thought Steve. I changed the O2 sensor about 100k ago. I remember when I replaced it the ECU gave me a code. Shouldn't I expect one now if that were the problem? I've considered replacing the sensors one by one, but they add up so quickly. I'm not against spending the money to fix it, but I don't want to waste any more money either.

 

Oh, can you explain how the EGR valve might cause this? I know it's responsible for sending fumes into the intake or back to the tank (I think), but it seems like it would be a lifetime part, no?

 

Ah, no it's not a lifetime part. It's probably "frozen" open or closed or the diaphram inside is ripped so it's not holding vacuum. Find the valve...put your finger underneath (on a cold engine) and in the space provided see if the diaphram moves up and down freely (but just because it does move does not mean it's good it just means it's free.

Glad to hear you've actually changed to 02 sensor. I'm impressed.



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This Product Fits the Following:Warehouse: CVehicleEngineTransmission• 1995 Toyota Tacoma2.4L 4 Cyl Automatic

And it's not CHEAP. Change out the PCV valve, too

Good luck

 

Had something similar with my /90 Mustang 5.0 L. Don't know if this will apply to your vehicle, but here is what I found. There is a filtre screen under the PCV valve that is usually missed by a lot of mechanics. It can become badly clogged over the years. You've got to pull the PCV valve and then use something like a corkscrew with a long handle to screw into the filtre screen in order to pull it out and replace with new screen. This alone got my vehicle back to normal operation. HTH.
Mark

 

I'll check into the EGR valve.
Is there anyone in Denver that could recommend a good Toyota mechanic? I'm tired of dealing with the dealers. They don't give a damn about a customer driving a 95 with no service history.

 

Ok, so I'm in the process of removing the EGR valve to take a look at it, and... I get engine oil out of one of the two larger hoses it's attached to.. After some googling, this doesn't seem like it's supposed to be that way. I checked the part# to be sure I really had the EGR valve. Any ideas?

 

Well, nevermind. I replaced the EGR and PCV valves. After further inspection it seems like it's not oil in the EGR vavle, it's more of a honey colored water. I'm not sure what that means.

So far it runs well, but I've only really taken it around the block. Sometimes it will run fine for a few days, usually after I open up the hood. I'll update later.

 

Update: after driving about 40 miles today I can say that the problem was not the EGR or PCV valves. Although the truck drives more smoothly than before, I still get the stutter and lack power unless I floor the pedal most of the time.

 

Fuel filter symptoms--fine at start up-after driving for while(times vary-dependant on fullness of filter) the engine will be STARVED for fuel. After a brief rest(engine off) the dirt will settle in the filter and you can run again. And it will get worse over time.
Another check-possibility--Cat converter clogged and getting REALLY HOT.
You may want to REPOST so you will GET MORE FEEDBACK!!
Check all VACUUME hoses and lines fo cracks and tightness. In a 95--you need to remember--they are 16-17 years old.
Dang you are too far away for me--Someone close by will help you out.

 

I didn't replace the fuel filter because the after 4 days of testing at the dealer, they didn't seem to think it needed it. I don't mind replacing it, but don't want to throw money at it without good reason. It doesn't display the behavior you mentioned, running fine at first and then starving later. It's completely random.
I don't suspect it's the cat, for the same reasons as the fuel filter.
I should probably replace the vacuum lines. I've inspected them, but that doesn't mean much. I'll see if I can get the right sizes and replace them this weekend.

 

You might wanna check the egr vsv under the intake manifold and see if it's operating correctly. It could be intermittantly working causing your sluggish issue. Water in one of those egr hoses shoudn't be. Good Luck

 

Could be your crankshaft position sensor. It helps the ecu adjust timing, and an intermittent short in the sensor or wiring would throw off the timing and cause your symptoms randomly.