2.9L Problems - Few different symptoms

Ok, it seems no one takes care of my Grandfather's truck when he loans it out. It has some problems and it's parked for the most part now while I try to trace them down.

The truck is a '87 Ranger 2.9L V6 4x4 Extended cab, Automatic, AC, with either 129k or 229k on it (not sure which).

Recently it got back from being loaned out at 5k overdue for an oil change. We got it in and had the oil changed, coolant flushed, and the ATF changed w/ filter.

But the problems are still present and here they are:

1.) When under a load you get a "putter" or "tap" sound out of the exhaust. It sounded really bad (like a pinging from the rear end or something like that) before we replaced the muffler. Replacing the muffler changed the volume and tone of the sound. This tells me it's definitely in the engine and we are hearing it through the exhaust. The only way to get it to occur is either load up the back w/ some weight or flat out stomp it from a stop or turn the ac on and do a semi-fast take off. Basically only when the engine is under load.

2.) It's gotten more gutless than it used to be. It's got less power than my '96 Subaru OBS w/ a 2.2L 4 Cylinder (literally) and both vehicles are within 200lbs of each other. The 2.9L V6 is supposed to have a little more horsepower and quite a bit more torque than that 2.2L 4 cylinder. The subaru is all wheel drive, so that should not be part of the problem.

3.) The idle is high. It sits close to 1k regularly, and over 1k w/ the AC on.

4.) Idle Fluctuations, but they are small ones. Say 800 to 900, or 1k to 1.1k, etc... Usually in neutral (not as much when in gear). Upon starting it (warm or cold) the idle will do some heavy fluctuations for the first few seconds of running before settling down.

So, where do I start looking? Ideas?

Did you have the fuel filter changed? Have you read the trouble codes? If you don't have access to a code reader a lot of auto parts stores will read them for you. There are a few other things to check. First thing you need to check your fuel pressure. If it is gutless under load and pinging it sounds like it could leaning out "not enough fuel". If that is ok then check vacuum. Vacuum will tell you how the motor is running if the fuel pressure is good. 30 to 40 psi. This will get you started on it. The are several things that could cause you trouble like this. The cat could be clogged or a vacuum leak.

This is an '87 so codes don't get read by most scanners. There is no CEL light on (yes it comes on w/ the key before starting as it should to show the lights working). But there may be codes I hadn't looked up how to pull them on this truck yet.

A quick history. In 2012 it decided to flat out die while I was driving it and wouldn't restart. It got new plugs, wires, fuel regulator, fuel filter, air filter, and finally coil (which was the problem).

Since then it has had between 8,000 and 10,000 miles put on it.

When the muffler was put on (just this last Friday) the cat was checked for flow, both of them. That was the major reason I took it up to the shop but after seeing how bad the muffler was I had them replace the muffler and tail pipe on it.

I'll see if I can rent a fuel pressure gauge in the next day or so and check that.

I have an 87 and a scanner and it reads all the codes.

Terry said:

I have an 87 and a scanner and it reads all the codes.

Click to expand...

There is no OBD2 Port on this truck. It requires a scanner that reads OBD1 Ford Codes and has the right connection for the vehicle.

The parts stores around here only have OBD2 scanners, which I have one of those and an OBD2 Bluetooth adapter to pull those codes.

Most OBD1 systems have a method to jumper the system and cause the CEL light to flash in sequence to identify any codes in the system. I just haven't looked up how to do it on this pickup yet.

I bought my tester at orielly and it was 45 dollars. I bought my fuel pressure gage at harbor freight. My tester is for obd1 fords.

+1 on Vacuum gauge, it can tell you alot
Good read here: http://www.gregsengine.com/using-a-vacuum-gauge.html

IAC(idle air control) valve reads like it is working since idle is changing but it also sounds like idle isn't stable, IAC Valve is basically a "controlled" vacuum leak run by the computer.
When engine is cold computer should run idle at approx. 1,100rpm, then as engine/coolant warms up idle should drop down to 700-750 for automatic, 600-650 for manual trans.
Computer has it's own coolant temp sensor, the ECT sensor, this is a two wire sensor located near thermostat housing.
Engine also has a coolant temp SENDER, one wire, that is for the dash board gauge, these are usually both located near each other.

After engine is warmed up, unplug IAC valve, idle should drop down to 500 or engine may even stall, either is good it means no vacuum leak.
If idle stays high then there is a leak, or someone has been messing around with what they thought was an "idle screw", lol, fuel injected engines do not have idle screws, no jets to suck extra fuel from.
So if that screw on the throttle linkage has been adjusted and is holding throttle plate open readjust it for 500 RPM with IAC unplugged, then plug IAC back in, RPMs should go up to 700-750.
You may have to unhook battery for 5 minutes to reset/reboot computer, it will then relearn new IAC setting and TPS(throttle position sensor) setting.

Cleaning the IAC valve can make idle more stable if it is sticking.
You can test the ECT sensor with a volt meter, 5volts IN, 3volts OUT when cold, .5volts out when warmed up, but for $6 you can buy a new one, make sure it is a SENSOR(2 wires) not sender, parts guys get them confused.

Any time you clean or change sensors/controls on an engine you should always reboot computer so it can look for an changes in system, it may act funny for a couple of drive cycles after this, that is normal.

And as trite as it sounds, run a can of Seafoam or similar gas treatment in the fuel tank.
Injector nozzles get dirty over time and drip fuel instead of spraying it, this can cause lean air/fuel mix which causes pinging.

RonD said:

And as trite as it sounds, run a can of Seafoam or similar gas treatment in the fuel tank.
Injector nozzles get dirty over time and drip fuel instead of spraying it, this can cause lean air/fuel mix which causes pinging.

Click to expand...

This doesn't sound trite. I actually just filled it up at Fred Meyer's w/ Premium and there Additech premium fuel additive (the expensive $8.99 one) for this tank of gas.

I appreciate the info on the IAC, and the ECT is in question as well in my mind but I didn't realize this had two. The dash temp gauge does not appear to be reflecting correctly. That's why I had them replace the thermostat when they did the coolant flush (other than I'm sure it was probably all gummed up from rust, etc...).

Also, if you have the part number on that reader I would be interested. On the website there is nothing that cheap for OBD1, they start at over $200.

For dash board gauges make sure the ground strap from engine to firewall is still hooked up that's the main ground for cab instruments.
Usually from one of the heads to the firewall, drivers side head is common.

To test temp gauge find sending unit on engine, remove it's 1 wire and ground that wire to engine or battery Negative.
Turn on the key and gauge should go up to HOT, remove ground and it should go down to COLD.
If that happens then gauge and wire are good, replace sender.

I scrapped the factory oil pressure and temp on my last truck. My pressure was always wrong. 45 dollars and I know what my motor is doing. I also converted to a gage cluster with a tach.

Terry said:

I scrapped the factory oil pressure and temp on my last truck. My pressure was always wrong. 45 dollars and I know what my motor is doing. I also converted to a gage cluster with a tach.

Click to expand...

His gauge cluster has a tach, it's an XLT Supercab.

This is what it does at an idle:

Well crap, I'll upload another video later. They cut the video off.

Have you done any more work on the truck?

Terry said:

Have you done any more work on the truck?

Click to expand...

Actually I have and haven't. I'm actually using the truck right now since I'm working on my '96 Subaru OBS (Outback Sport). It's getting an upper end rebuild and lower end reseal (by me).

What I have done on the truck was disconnected the MAF (unintentionally I was tired and confused the IAC and the MAF, I know different spots entirely but I hadn't looked up locations yet).

When disconnecting the MAF there was literally "NO" difference in the way the truck ran. This concerns me because usually when you disconnect a MAF it makes a difference.

I did order a Ford OBD1 Code Reader + extension cable from Amazon that is supposed to be here tomorrow.

This should be the correct video. Warmed up at an idle in a parking lot with a fluctuating idle.



It does have a miss at idle, you can feel it but not hear it.

At this point I'm sure something is messing w/ the fuel to air ratio, especially when under a load.

I finally figured out how to describe the sound when under a load (i.e. weight in it or taking off from a stop rapidly, etc...). If you ever put the card in the spokes of your bicycle and then started going fast, it almost sounds like that. Except this comes from the exhaust.

To add I know we replaced the coil, fuel filter, air filter, and I think plugs/wires within the last 10k miles (about 3 years ago) along with the pressure regulator.

Have you put a fuel pressure gage on it yet. My high pressure pump. Was under the low pressure. When the truck was shut off the pressure dropped to zero. I changed the pump and the screens on the tank pump. It ran great after that.