My 86 has a EFI 302 with an AOD auto. It always starts RIGHt up but it warms up and runs REALLY crappy/ loping,surging/ missing/shaking the truck acting like it wants to die. But it does not do it all the time maybe 80% and other times it runs perfect. When it does run crappy though and I give her gas and it will respond instantly and run great. It runs exellent down the road.
I have heard. injectors
o2 sensor
dirty EGR valve
bad IAC valve
intake manifold gasket
and the cross over tube for the exaust on the back of the motor that is broke off.
I want to replace the cross over tube but I don't know what to ask for at an exaust shop and how much it will cost. any ideas?

 

anyone?????
I'm in the dark on this one I guess

 

sounds like your egr vavle to me, my 86 with a 300 did the same thing, i made a plate for where the EGR vavle goes and it fixed it up real good, might wanna try a plate for it, and if you wanna keep the egr, then get a new one, they arent too much.

edit: losing your EGR can increase power, and gas miliage, but ive heard it over heats your cats...but ive never had a problem with it.

 

All the EGR Valve does is mix exhaust gases back into the intake to be reburned. I don't know how it would have any effect on cats. Maybe someone can enlighten me.

 

thats what i said, them i got yelled at. hehehe

but who knows huh?

 

Also I just noticed Thier is a "ticking coming from the computer /wiring right on pass side beside the battery that comes and goes

 

Wow, what a myriad of problems you could have. Is the check engine light on? If so, what are the codes coming out? The first thing I would look for is a vacuum leak. Particularly in the PCV hose going from the valve cover to the back of the manifold. The elbows for the hose turn from rubber to some unidentifiable substance. Once they are soft and mushy, they develop a hole. The leak is probably somewhat interrmittant as it works sometimes. A leak can cause the egr valve not to open correctly. A vacuum leak can cause a slew of other codes to come out of the computer including lean condition codes. The EGR circuit can also plug up. There is a passage under the valve that plugs up with crap.

Injectors are not likely the problem. They seldom cause intermittant problems. Pretty much work or don't.

 

like i said...jsut make an egr plate and see what happens

 

I would get a code scanner for $30 then dump the codes and see what the computer says is wrong first.

 

The compuer will not pull the code as it says "truck not responding" So I don't know. CAN the cross over tube be causing ALL of this?
Where do I get the cross over tube asymboly? It is the tube that is on the back of the motor into a "T" that broke.

 

I would find out why your computer isn't responding as if the computer is dead that could be causing your problems.


It could just be a broken wire to the diagnostic plug but the computer could also be fried and your truck is just trying to run from emergency mode.

As for the tube, you could weld it or find a replacement from a junkyard. Unfortunately I didn't keep that piece from my donor vehicle or I would send you one.

Good Luck,

Lee

 

Dustin_86, I too get the clicking from the bank of relays or whatever they are behind the battery sometimes. It does seem to make the idle jump up and down. If anyone knows what is causing this I am interested as well.

 

This early fuel injection system is comparatively complex and not well understood. A Ford EEC-IV scanner or dual trace digital oscilloscope is needed to check:
1) that the two oxygen sensors (3.8L only) are switching together and nearly equal in amplitude (the 5.0L has only one O2 sensor);
2) fuel control at idle, by forcing the mixture rich, then lean;
3) fuel control at light and medium loads.
The air injection system can switch upstream and downstream (of the oxygen sensor) for catalytic converter overheat protection. Air injection will switch to upstream at 30-45 seconds at idle, forcing the mixture rich. Ensure that air switches downstream as the throttle is opened. The air injection switching solenoids are located below the coolant overflow bottle and are subject to rust, dirt and corrosion.
This system is extremely sensitive to low manifold vacuum, a typical condition for an older vehicle at our altitude -- check timing chain, ignition timing, carbon buildup, exhaust back pressure and leaking EGR problems. Verify manifold absolute pressure frequency at or near 102 hz at idle. Fuel pressure is another critical area. It is not uncommon for these systems to be running at or near 45 psi. Ford specification is 37-40 psi; check and adjust to the low end of this specification at the throttle body as necessary. (Do not set below 37 psi!).
The left pin in the center group of 4 pins is the Self Test Output pin (STO). The single terminal hanging loose is the Self Test Input pin (STI). To run the test, you must either have a Check Engine light, or hook up an analog voltmeter. If you have the Check Engine light ('87 and later cars), just watch it during the tests- it will flash the codes. Otherwise, hook up your voltmeter between the positive terminal of the battery, and the STO pin above- you'll count its needle sweeps to get the codes. The FP test pin, when grounded, runs the fuel pump continuously - but that's just FYI. You won't deal with that pin for these tests. To enable the KOEO test, connect your wire jumper between the STI pin (dangling off by itself) and the Signal Return pin above. Then, turn the ignition on, but don't crank the starter- the EEC-IV will enter the KOEO test. During this test, 5 things will happen.
First, you'll hear a bunch of clicking for a few seconds as the EEC-IV exercises its valves and actuators, and takes readings from its sensors.
Second, if you're using a voltmeter, you'll see a series of very fast pulses go by- they may register a volt or two. These are the "fast codes" that the real STAR scan testers use, but they go by too fast (100x the normal scan rate) to be of any use to us. If you're watching the CE (Check Engine) light, you won't see anything.
Third, you'll get the on-demand codes- these indicate what the EEC box has found problems with _at the moment of the test_. They will be presented to you as either flashes of the CE light, or sweeps of the needle on the voltmeter. The code 21 would be presented as flash-flash, pause, flash. The on-demand codes will be presented twice- if the EEC-IV has found nothing wrong, it will give you code 11, twice: flash, pause, flash, longer pause, flash, pause, flash. The flashes and pauses for a given digit are each 1/2 second. The longer pause between digits are 4 seconds. The longer still pauses between codes are 6-9 seconds. If you'd like to see a code just to see what they look like, leave the trans in gear (MT) or drive (AT), or push in the clutch- and you'll get code 67 repeated twice. If there is more than one code detected, they will be presented in sequence, twice: 22, 47, 22, 47.
Fourth, you'll get the separator code. The Ford manuals call this code 10, but you can't see the _absence_ of a pulse for the 0- you'll just see a 6-to-9 second pause after the last "on-demand" code, then a single flash.
Fifth, you'll get the "continuous" codes- these are the codes that the EEC-IV has stored in its non-volatile memory from events that have occurred while you were driving in the past. Another 6-to-9 second pause after the separator code, and you'll get another sequence of 2-digit codes that will look exactly like the on-demand codes. If all is well, you'll once again see 11,11. So for example- if at some point in the past your throttle position sensor has wigged out while driving, you'll get a 23 in the continuous codes. If it's still wigged out at the time you start the test, you'll see it as a 23 in both the on-demand and continuous codes.
One last item is how to clear the continuous codes, so that you can see if new ones crop up. This is simply done by disconnecting and then reconnecting your jumper after all the tests have been run and the codes have been received. Pretty simple, _very_ powerful. Unquestionably your friend. Perhaps there's something to this computer stuff, after all.
To do the KOER test, set the car up as above. Then with the STI/signal return jumper disconnected, start up and run it at 2000 RPM or so for two minutes, to thoroughly warm up the EGO sensors and get everything stable. Shut down, reconnect the jumper, and immediately restart, and the EEC-IV will go into the KOER test. Several things will happen. The first is that you'll get the engine ID code- 2 pulses for a 4-cylinder, 3 pulses for a 6, and 4 for a V8. Then the EEC-IV will begin playing with its actuators and sensors, trying to fool them into going to the extremes of their ranges. During this interval the car will run very poorly at times- it may go rich, lean, stumble, buck, and do all manner of unpleasant things. This will last from 6 to 20 seconds. After this interval, the motor will smooth out and begin an even idle. You will then see a single flash or sweep of the needle. This is the Dynamic Response code, which is your cue. After this code, you have 10 seconds to snap the throttle wide open, just long enough to get above 2000 RPM. Once the engine gets above 2000 RPM (it won't take long at WOT with no load!), release the throttle, and let the engine go back to idle. This part is lovingly called the "goose test". The EEC-IV needs to see what happens at high throttle settings to make sure all of its sensors and actuators work properly, so you get to help out by goosing it. This test will last from 4-15 seconds. The goose test is followed by fast codes (which only those of us stuck with a meter will be able to see, and we can't do anything with them), followed by the KOER on-demand codes exactly as above. If all was well, you'll get 11-11. If you didn't goose it enough, you'll get a 77 and get to do it over again. At this point you can optionally run the SEFI or Cylinder Balance test. If you have an '87 or later, lightly tap the throttle (it only takes a small movement) WOT), and release it. Owners of '86s will have to go WOT briefly. After a little while, the EEC-IV will begin cutting the injector to each cylinder in turn, and looking for a drop in RPM. If there is no drop associated with any individual cylinder, then there is some problem there (that may or may not be related to the injection system- you could have a valve problem, or a fouled plug, or a shop towel stuck in the intake runner, and get the same effect). This test takes about 90 seconds. If a cylinder is found by this test to be weak, a single-digit code will be flashed telling you which one (1-8). If all is well, the code will be 9. If it gives you a 77, it got confused (perhaps you bumped the throttle) and you need to start over and rerun the test. '87 and later cars can then rerun the SEFI test after it finished, again by just tickling the throttle (saves having to go back through the whole KOER test). It also relaxes the criteria for "fail" with each retest, so if one cylinder fails the first time but passes the second, it's only a little weak- whereas if it fails 3 times in a row, it's profoundly dead. Those of us with '86s have to go back to Square 1 to rerun, and we don't get this progression of thresholds to help us troubleshoot.

 

With computerized engine control systems, it doesn't take much of a sensor input problem to adversely affect drivability and emissions. A sluggish O2 sensor, a defective coolant sensor that always stays cold, a throttle position sensor that has a dead spot, an airflow sensor that isn't reading accurately, etc., can all hurt performance, fuel economy and emissions. In an attempt to ratchet up the self-diagnostic capability of PCMs, the California Air Resources Board developed a "next generation" onboard diagnostic system called OBD II. "OBD" is an acronym for "On Board Diagnostics." The "II" stands for "second-generation system." OBD II first appeared in 1994, and it has been required on all cars and light trucks since 1996.
Unlike earlier onboard diagnostic systems that set a diagnostic trouble code only when a sensor failed or read out of range, OBD II monitors most engine functions while the vehicle is being driven. It is designed to detect almost any problem that can cause emissions to exceed the federal limit by 1.5 times.
OBD II is extremely sensitive. Some say it is overly sensitive because the vehicle manufacturers have been overly cautious in setting trigger points below the 1.5 threshold to reduce the risk of expensive emission recalls. As a result, some vehicles may not actually have an emissions problem when the Check Engine light is on. Nevertheless, the problem should always be investigated to determine the cause.
The check engine light, which is technically called the "Malfunction Indicator Lamp" or MIL, is supposed to alert the driver when an emissions or sensor problem occurs. Depending on how the system is configured and the nature of the problem, the lamp may come on and go off, remain on continuously or flash - all of which can be very confusing because you have no way of knowing what the light means. Is it a serious problem or not?
For example, let's say a vehicle has an OBD II code for the oxygen sensor circuit (code P0130). The code might indicate a bad sensor, or it might indicate a loose connector or wiring problem.
Harder to diagnose are misfire codes. OBD II can detect misfires in individual cylinders as well as random misfires. If it generates a misfire code for a single cylinder (say P0301 for the #1 cylinder), it only tells you the cylinder is misfiring - not why. The underlying cause could be a bad spark plug, a bad plug wire, a weak coil on a distributorless ignition system (DIS) or coil-on-plug (COP) system, a dirty or dead fuel injector or a compression problem (bad valve, leaky head gasket, rounded cam lobe, etc.). As you can see, there are multiple possibilities, so it takes some diagnostic expertise to isolate the fault before any parts can be replaced.
A "random misfire code" (P0300) is even harder to diagnose because there can be numerous causes. A random misfire usually means the air/fuel mixture is running lean. But the cause might be anything from a hard-to-find vacuum leak to dirty injectors, low fuel pressure, a weak ignition coil, bad plug wires or compression problems.
Something else to keep in mind about OBD II fault codes is that some codes are false codes. GM has had problems with certain 3.8L engines setting P1406 codes, which indicates a fault in the EGR valve. Replacing the EGR valve doesn't fix the problem because the OBD II system is overly sensitive to how quickly the EGR valve opens when it is commanded to do so by the PCM. The cure here is not to replace the EGR valve but to "flash reprogram" the computer so it is less sensitive to this condition. Referring to vehicle manufacturer technical service bulletins (TSBs) can save a lot of time and frustration for these kinds of problems.
Something else that complicates diagnosis is that "standardized" OBD II codes really aren't. There are actually two different types. "Generic" OBD II codes are the same in the sense that all vehicle manufacturers use the same code numbers to indicate the same type of problem. But each vehicle manufacturer also has their own special "enhanced" codes that cover problems not included in the basic OBD II code list. These include many problems not covered by the generic codes as well as problems that are outside the engine management system such as ABS codes, climate control codes, body codes, air bag codes, etc.
Generic OBD II codes all start with "P0" while the OEM enhanced codes all start with a "P1." Enhanced codes are often vehicle specific and require a high-quality scan tool such as the AutoTap OBDII scantool for PC or Palm. Diagnosing computerized engine control systems and sensors isn't an easy task, but that's the price we pay for drastically reduced emissions and the feature-laden vehicles we drive today. So do your diagnostic homework before you replace critical engine management system parts. It will save you frustration and needless returns.
A couple of things to keep in mind when replacing sensors: Parts that are physically interchangeable may not be calibrated the same and won't work properly if installed in the wrong application. To make sure you get the correct replacement part, it may be necessary to refer to the vehicle VIN as well as OEM numbers on the original part. Some aftermarket parts may not look exactly the same as the original. A "universal" O2 sensor, for example, may fit a large number of applications but usually requires cutting and splicing wires to install.
Though most O2 sensors have no recommended replacement interval (replace "as needed" only), sluggish O2 sensors can be replaced to restore like-new performance. Unheated one- or two-wire O2 sensors on 1976 through early 1990s applications can be replaced every 30,000 to 50,000 miles. Heated three- and four-wire O2 sensors on mid-1980s through mid-1990s applications can be changed every 60,000 miles. And on OBD II equipped vehicles, the sensor could be replaced once it has seen 100,000 miles.

 

Tried to pull codes on an oldsmobile yesterday. My scanner didn't come on when I plugged it in. The power feed in the obd plug is on a fuse and the fuse was blown. I had to check all of the fuses since it wasn't listed on the sticker on the fuse cover. You may have a blown fuse that is causing you problems.