Odd Stuttering for 22-RE

1988 SR-5 Pickup, 22-RE 4 Cyl. 2.4 liter Engine, 5-Speed Manual, fuel injection. No AC.

Problem: Engine stutters for a couple of seconds when I step on the gas, but ONLY when accelerating AFTER I was traveling along and allowed the engine to brake the truck. This is the case when I eventually come to a stop and also if I never fully stop. After the stuttering, it runs great even when under heavy load like traveling up a steep hill.

Here's the odd part: If I take it out of gear just BEFORE letting the engine slow the truck, and allow the RPM's to drop to idle, then put it in gear and accelerate...no stuttering!

It's as if something were loading with fuel when I let off on the gas pedal and allow the engine to brake, resulting in a too rich mix when I accelerate again.

I put in a new timing chain last year and the engine ran fine for several months.

Items replaced with no effect on stuttering: Spark plugs, ignition wires, distributor cap, rotor, PCV valve, air filter, fuel filter. I checked fairly rigorously for vacuum leaks.

Any Ideas? Thanks Tony

Reply to
Tom Sweazy
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Have you ever cleaned the throttle body? Its gets carbon and black greasy oily stuff in there - use special cleaner for throttle body (or spray carb cleaner) and rag. Probably do better job with it removed but that's a real pain.

Reply to
Wolfgang

you probably have a leaky fuel injector.. have them tested.

Reply to
Guylaine J. Parisien

Hi Wolfgang, Thanks for the suggestion. I have cleaned the throttle body, but it was a couple of years ago so it's worth another try (that is as soon as the snow and wind let up here in the northeast....brrrrrrrrrrrrrrr. Tony

Reply to
Tom Sweazy

Hi Guylaine, Thanks for the tip. Wolfgang suggested cleaning the throttle body, which I will pursue. When you say that an injector may be leaking, does that imply it allows fuel to pass through when it should be shut off during deceleration? If so, that would seem consistent with the symptoms. Do you know what's involved in checking for a leaky injector? Does it require special equipment? Tony

Reply to
Tom Sweazy

To test ya need special equipment -- You can pull them all and ship to RC Engineering or DOA racing (if I recall) to have then cleaned and calibrated.

Reply to
Wolfgang

Hi Wolfgang, Thanks for the info on the injectors. As soon as the weather breaks and I can schedule some downtime I'll most likely go for it. By the way, when the engine is warm and I'm idling, sometimes there's a very low level pop/skip/stutter and most people don't even notice it. The tach barely shows a drop in RPM. Could this be related to the injector problem addressed earlier? Some folks have said it's normal for a 4 cylinder engine. I don't recall it doing that before but maybe I never listened close enough. Tony

Reply to
Tom Sweazy

Use injector cleaner. Run the fuel tank down to 1/8-to-1/4 full and pour the whole bottle of injector cleaner into the gas tank, then drive it as far as you dare before you run out of gas, [don't ever run out of gas with fuel injectors] then fill the tank, run it to 1/8 and do it again, then add cleaner to each tank full after that according to directions on the bottle. You can't put an overdose in the tank and leave it as it will melt the seals in the fuel system if left concentrated for too long. This is what my toyota dealer does to first time problems, then if this doesn't fix it, it's remove and replace. Fuel injectors on stationary diesel engines etc are re-buildable but I don't know about the Toyota units. I doubt it as the service manual only refers to replacement. The manual shows the test procedure for volume flow and leakage. ( less than one drop of fuel per minute) Remove the injector from the engine, jury rig a hose to the input [use fuel from the pressure regulator] jumper the fuel pump so it runs without the engine running. . Both the cold start and cylinder injectors should be the same leakage. They also specify flow, put power to the injector and see a nice conical spay pattern as well as measure the output..

40-50 cc / 15 seconds, variation less than 6cc across all injectors. don't leave the injector powered longer than needed.

Reply to
Guylaine J. Parisien

Hi Guylaine, Wolfgang,

I tried the 1/4 tank injector cleaner technique and the stuttering has gone away! I filled the tank and still no stuttering after about 50 miles from the original treatment. This will certainly save me $$$$ if it holds. I had forgotten to mention I had tried a can of BG44K in a full tank a few weeks ago but that had made no difference. Perhaps it would have if I tried the 1/4 tank method. I used 'Valvoline SynPower Fuel Injector Cleaner" this time around. I still plan to clean the throttle body. Thanks again both of you for taking the time to respond to my question. Tony

Guyla> Use injector cleaner.

Reply to
Tom Sweazy

Reply to
scott and barb

My 92 22refi is doing exactly this too I used the BG44k $$ too, same thing, it sorta helped but not much. Then I tried the 1/8 tank w/ full can of AutoZone ?brand injector cleaner, ran 1/8 hard in it and refilled, its working better now. ALSO, NOTE: I cleaned the little filter on the EGR vacuum module, it comes out easy and mine was very dirty. It helped. Also, mine runs correctly when its cold, still choked I guess, then starts acting like this as soon as it warms. It still does what yours does a little, but its not as bad now. If you find somethig else that improves it (my Gas milage was only around 22mpg) let me know on the group. I am running the next tank of premium and I i will have to see if the milage improves. What should I expect with this 22re?? I heard you can get 30mpg if its running right.

Reply to
Cregster

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