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I am having expensive trouble diagnosing a recently acquired engine stumble in my 1989 4x4 long bed, 5sp, 22re pick up. 160,000 miles, one owner(me).
I live at 8,750' elevation in the mointains in CO. Truck has been almost trouble free until recently.
Started out needing new water pump. At the same time I had developed a leak in the transfer case seals. Also had front wheel bearings and races replaced. All done by a trusted mechanic with much experience with the 22re. I mention there is also inter mittent engine stumble that has developed.
Stumble is always in the range where one could be in one gear or the other. So it seems to happen around 40 and around 25. Most consistent way to reproduce it is when pulling up the long hill to the town I live in. Top out on hill in 3rd gear. Shift to 4th. Drive slowly along flat valley with decreasing speed limits while approaching into town. Not giving gas but kind of coasting along. Give light gas to maintain speed and engine stumbles/misses. Also happens in 3rd and/ or 2cnd when same type of driving and getting closer to town. Does not happen when driving at speed and/or pulling up hills.
Mechanic checks spark plugs, wires, rotor, cap, coil and it all checks it good. He determines the EGR is not functioning correctly. Recommend replace and Also recommends valve adjustment. Doesn't really experience ithe problem on test drive but believes me that there is a problem.
Note - Shop is at 5,750' and a 3 hour round trip drive from home.
I bring it back for EGR and valve adjust and it is discovered that the timing chain guides are broken and missing and pieces are laying in the oil pan. Yikes!!!
New timing chain, new EGR, and valve adjust. Engine stumble remains. Mechanics still don't feel it during test drive. Mechanic also says radiator fan blades are cracked and fan should be replaced for safety reasons. Also do compression test. About 155 on all cylinders
Bring it back for fan and take longer test drive with Mechanic who now experiences what I 'm talking about but it seems mild and barely noticeable to him. To me it's very noticeable, but maybe less so at the lower elevation of the shop? It can almost be mistaken for hitting small bumps in the road and is difficult to discern on bumpy roads.
More testing. Codes come up with 24-Intake air sensor, 31-Air flow meter sensor, and 41- TPS. Decide to replace TPS. Engine stumble remains.
Mechanic says it's so minor just drive it. I don't like it and want to fix it. It's unsettling to me to drive around with this occurring and definitely not what I'm used to with the truck. Friends notice it, I notice it, girl friend notices it. Maybe more so at altitude.
Now I'm thinking of replacing the Mass Air Flow Meter.
My questions:
Is replace MAF a logical next step?
Could a non mechanic but somewhat proficient DIY do this? I can change plugs and oil and do simple mechanical stuf not requiring specialized tools. I have standard and metric sockets and wrenches and etc.
Was planning to order this and try installing it myself.
My opinion is that I would not replace anything without knowing if it's bad if possible. I would downshift and drive it. Lugging an engine will make it do bad things. When I get in that situation I down shift, as some have stated this engine seems to like RPM's. Also you're at 8750' altitude, It could use a little help up there. I'm at 4100' elevation and notice it.
I don't feel I'm excessively lugging the engine on these occasions. This is a relatively new problem that has recently arisen. Something is making the engine miss/stumble.
Check for cracks in the air inlet tube from the filter to the throttle body. mine had same symptoms and found a crack in the elbow of the tube. Duct tape it shut as a short term fix and no more stumbles on accel.
I don't feel I'm excessively lugging the engine on these occasions. This is a relatively new problem that has recently arisen. Something is making the engine miss/stumble.
That's good. I didn't mean to sound accusatory. Sorry. After re-reading it, it didn't just sound like my opinion. kcaudill has a good point, good thing to check.
I looked for cracks in the "tube" that come off the air filter. I think you mean the large diameter tube that goes into the end fuel injector/throttle area right where the accelerator cable attaches? (The large end elbow/fitting is visible in the attached photos). No cracks visible along any of that.
I did notice a small electrical connector that's not connected to anything. can't see where or what it would/should be attached to.
I believe the wire you have pointed out is used if you have A/C but I'm not 100% on that.
It's been said that all the trucks of a given generation are equipped with the same wiring harness. If everything is working fine don't worry about a connector that isn't plugged into anything.
My 91 doesn't use the wire you have pointed out and there is also one that lies between the valve cover and the intake plenum (pictured below) that isn't used either. That one definitely goes to the A/C, which I don't have.
What follows is a pretty cheap thing that may or may not help your problem. Either way it will probably improve the way something on your truck performs.
It's pretty dirty under that hood.
I can't help but notice the nastiness around the ground cable that's connected to your block. I'd say it's a good time to replace that ground cable (maybe the positive cable too) and clean up all of your ground and power wires. Bad wires and high resistance/dirty connections have given thousands a headache. Don't just look at them and say they are good. That has fooled many and they start replacing parts that weren't bad. From time to time automotive shops and dealerships still make this mistake and who pays for that? Remember that the vehicle uses a crude computer and if the connections, grounds, and power cables aren't in great shape the engine management system (fuel, spark, etc) is going to be functioning with a handicap.
The factory Toyota battery cables are minimalistic.
After many years of continued use the copper wires inside the battery cables will start to suffer and will loose some of their ability to allow voltage to flow easily. They create resistance reducing the flow of voltageeven if the connectors have been cleaned or replaced.
It doesn't matter if it's a dirty/bad connection or a bad wire with high resistance, lower voltages can create Driveability problems, weaker ignition spark, starting problems/slow engine cranking rpm, dim headlights, dim tail lights, low heater air velocity, slow windshield wipers etc.
People say the factory cables are 6 awg but they are probably a little thinner than that. Most recommend that you replace them both with at least 2 awg cables. If you can't make your own you should be able to find some premade 2 awg cables that will work pretty easy. I've seen where a couple of people have said they used a 1 awg cable from a Chevy truck. Generally the smaller the number the thicker the cable until you get to the fairly serious stuff like 1/0, 2/0, 3/0, 4/0.
Below is the 22re ground wire guide.
Remove each ground and power wire connected to the battery and clean it. If you can move it with medium force after tightening it down it's too loose.
To say grounds are important is an understatement especially on a vehicle that is equipped with a computer- ECU/ECM.
Although there isn't a guide the power wires should also be treated the same way.
If you find a ground wire is missing look around for it, sometimes people forget to hook them back up after engine work. If it's broke or missing make a new one from at least 10 awg wire to replace it. Some people go one step better and replace the smaller wires with 8 or 6 awg which is great. If you make simple crimp connections do yourself a big favor and use adhesive lined shrink tubing to help keep corrosion out of the joint.
Treat all of the connections in the following manner.
1. Go to the store and purchase a small brass bristle brush and a tube of dielectric grease.
2. Dealing with one connection at a time, unbolt the connector and use the brush to clean the area the connector makes contact with until it shines.
3. Clean the ground wires connector with the wire brush until it's absolutely clean.
(The idea here is to have fresh shiny metal to metal contact for maximum voltage transfer between the connector and whatever it's connected to.
If there's a ground that is bolted to paint or rust you'll of course need to remove the rust or paint to get good metal to metal contact.)
4. Apply some dielectric grease to the connector and bolt the two back together.
Dielectric grease will HELP keep corrosion away but it won't stop it. You'll eventually need to clean the grounds again. That's just the way it is because of the environment your dealing with.
Here's what happened when I went through and cleaned up the factory grounds on my truck:
When I got my 91 truck it had all the factory wires. Under the hood I found a small ground wire that was broke and one that was needing to be replaced. I replaced both with 8 awg wire and cleaned up all the underhood connections in the 22re ground wire guide and it helped to a small degree. It actually got rid of one of my CEL codes, it started easier, and smoothed the engine out a little.
Months later I took the interior kick panels off both sides and found some more grounds down there. One of them is the ECU/ECM ground, I think it's the connector with the brown wires. It's very important to keep that in good shape. I cleaned them all up and I think my heater started blowing harder, it seemed like my dash lights got a little brighter too. This was several months ago so I'm not 100% on that.
At first I didn't bother replacing my factory battery to engine ground cable because it looked to be in good shape with no bulges, no green coloring, and no white growth. I just cleaned the ends good and applied dielectric grease and called it good.
Now, about a year later I finally got around to replacing that cable with a 1/0 gauge cable because I hate how thin the factory one is.
That made a pretty good difference as the motor spins over faster when cranking and it seems to have also added driveability by smoothing out the engine through the low-midrage rpm's a little more.
Yes that is the connector and you identify it as being for AC which I do not have on the truck.
Very helpful. Agreed the engine compartment is dirty, esp. When compared to the photo you included.
I will checkout the wire and ground issues you brought up. I have replaced the battery cable terminal ends. Also used a spray product on each terminal made for the purpose of anti corrosion and etc. As part of the mechanics trouble shooting he replaced/serviced the battery ground wire. So that has been recently done.
My question remains regarding the MAF. I am thinking of going thru the ohm meter test. If that tests out OK is it possible that could still be the problem? I have a high index of suspicion for that part. Due to process of elimination, code that was indicated, possibly problem is worse at higher altitude.
This may be a stretch, but I swear he first time I experienced this miss/stumble was on my first trip to the shop for the wheel bearings, transfer case seals and water pump. I went thru an area where there was a rock/cliff side being blasted away at to straighten a curve. Lots of dust in the air. Was stopped by flag person for 20-30 minutes. Started going again and whamo, dramatic miss fire. After that I couldn't be sure if it had been my imagination or if it was continuing inter-mittant, or just bumps in the road or....? Now I know it's happening and so do others who ride in the truck.
So maybe some rock dust got on something? I think ther may be some diode or such in the MAF but it cannot be cleaned? Possibly the part could check out OK with the ohm meter but still have problem like I'm guessing at?
possibly the 02 sensor. if the mixture is not rightit can do any nuber of things. it's just one of those once in a while tune-up items. btw, 4awg wire will do fine for anythin on this truck. 2awg would be like if you are mounting jumper cables on the rear bumper.
The mechanic checked all the sp wires, plugs, rotor, cap and coil a according to him all OK ( see very top post in this thresd).
Also should mention, Truck starts like a champ and always has. As soon as the key is turned it fires right up and idles just right.
Is there any way to test the O 2 sensor?
Still hoping someone can weigh in on wether testing the MAFM with an ohm meter is a definite bad/ good test. If it checks out OK with the ohm meter test could it still be bad?
OK I tested the MAF with an ohm meter per the instruction in the link above.
I took the air hose off and inspected it including it's under side. No cracks, it looks fine.
The ohm meter test did not match the spec. When measuring between E1-FC in door fully closed position should read infinity I was getting no reading at all from the meter, is that equal to infinity? When measuring from E1-FC with door in any position other than fully closed it should read 0 but when it was fully it was reading 180. The other measurements between other terminals did appear to match the spec.
Infinity is an open circuit. So, my understanding is no reading on your meter. That is what shuts off you fuel pump. No continuity with the door closed, continuity with it open. Did the other readings look good? Have you checked the TPS? (sorry don't remember)
When measuring from E1-FC with door in any position other than fully closed it should read 0 but when it was fully open it was reading 180 - so out of spec. The other measurements between other terminals did appear to match the spec.
The TPS was replaced last week as part of this ongoing trouble
Oh, sorry, thought you meant just E1-FC. If they are out of specs per the book. If it was me I would think it's a problem. (That's like a disclaimer statement!)
Infinity should be the same reading you see when the probes aren't touching anything. I would think 180 is OK, to me the ECU is looking for anything but infinity or open. (I never liked infinity, confuses my pea brain!)
180 is not okay. it drives the relay coil, so like only 200ma passes through it, but 180 would probably not get close enough to 200ma current to hold the fuel pump on. get a box cutter and slice through the silicone on the cover. i'll attach a pic here but the second (beefy) terminal can be pushed up or down some to get the point contacting in another spot. don't try to manipulate the first tang on the left, just the second, and don't let it rest on the circuit board when done. don't forget to touch the meter terminal leads together and subtract that reading from your reading. do it before and after measuring. less than 10 ohms should hold the coil open, but something like 0-4 is good afaik.
Last edited by AKHeathen; 09-03-2015 at 12:19 AM.
Reason: forgot image
btw, 0 is always no resistance, and like .02-.20 is typical of when you touch the leads together and should be concidered the point of "zero" on your meter. infinate should show like "ol" or whatever it shows when the leads are touching nothing but air.
08-30-2015, 02:38 PM
