Detonation problems

click on link.

http://www.muscularmustangs.com/test2.php

Well, are you sure the egr valve is actually working?

i would start by testing the o2 sensors with a multimeter a repair manual will tell you how to test yours i had- Fuel pump primary circuit failure& HEGO sensor circuit indicates system lean. you probibly have a bad o2 sensor replace if bad and clear codes drive and pull codes again might clear all of them up and might not if not repost in thread codes recieved until we help you clear all of them and good luck.

bdazzgt said:

yea the EGR works because if i hook it up to raw vaccum it opens so i know it works.

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Just because the diaphram moves doesnt mean the EGR is functional. If you apply 5-6" of vac to the EGR nipple, does the idle stumble or even die? It should. The EGR passages can coke up so bad that the inert gasses dont flow as substantially as they should. A bore brush can clean the passages out.

The EVR relates to the computer how far the EGR valve is open. The EVR can be out of calibration or the EGR can be hung up so it doesnt seat where it should.

FWIW, you can search on individual code numbers and then read Jrichker's posts on each. His info is very informative and hard to beat in terms of providing an understanding of the component, as well as how to troubleshoot it.

Good luck.

bdazzgt said:

thanks hissin how do i know how much vac i applied i dont have a gauge or anything to check that with. if i put any engine vac directly to the EGR silenoid it stumbels and dies.

Click to expand...

It sounds alright. Applying 15-20" of vac really slams the diaphram, so I use a vacuum gun (which has a gauge, so I can apply about 6" and watch the diaphram move). But it did what it should when you applied the vac.

Good luck.

Code 14 - Ignition pickup (PIP) was erratic – the hall effect sensor in the distributor is failing. Bad sensor, bad wiring, dirty contacts. You have to press the distributor gear off the shaft to replace the sensor. The pip signal is used for ignition timing and fuel injector timing.

Code 29 - Vehicle Speed Sensor (VSS) is an electronic sender mounted on the speedo pickup gear on the trans. It works the cruse control for both 5 speed and auto trans cars. The VSS is used to tell the computer to speed up the idle as you slow to a stop. This helps keep the engine from stalling when you slow down for a stop sign or stop light.
Check to see if the electrical connector is plugged into it. Clean the connector & contacts with non flammable brake parts cleaner prior to replacing the sensor, as that may fix the problem. The sensor cost is under $30 and it is easy to replace.

CODE: 31 (KOEO) - EVP circuit below minimum voltage. Vref (5 volt reference voltage supplied by the computer) missing or broken wire or bad connection in circuit. Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or MAP sensor located on the firewall near the center of the car. Use the black/white wire for the ground for the DVM.
With the sensor removed from the EGR and still connected, press the plunger and watch the voltage change on the brown/lt green wire. Pull the passenger side kick panel and measure the voltage at the computer. You will need to remove the plastic cover over the wires and probe them from the backside. A safety pin may prove very useful for this task. Use pin 27, EVR input (brown/lt green wire) and pin 46, signal ground (black/white wire) to measure the voltage. The orange/white wire is Vref and should always be 5 volts -/+ .25 volt. Be sure to measure Vref at the EGR sensor to rule out any broken wires or bad connections.

Code 41 or 91 - O2 indicates system lean. Look for a vacuum leak or failing O2 sensor.

The computer sees a lean mixture signal coming from the O2 sensors and tries to compensate by adding more fuel. Many times the end result is an engine that runs pig rich and stinks of unburned fuel.

The following is a Quote from Charles O. Probst, Ford fuel Injection & Electronic Engine control:
"When the mixture is lean, the exhaust gas has oxygen, about the same amount as the ambient air. So the sensor will generate less than 400 Millivolts. Remember lean = less voltage.

When the mixture is rich, there's less oxygen in the exhaust than in the ambient air , so voltage is generated between the two sides of the tip. The voltage is greater than 600 millivolts. Remember rich = more voltage.

Here's a tip: the newer the sensor, the more the voltage changes, swinging from as low as 0.1 volt to as much as 0.9 volt. As an oxygen sensor ages, the voltage changes get smaller and slower - the voltage change lags behind the change in exhaust gas oxygen.

Because the oxygen sensor generates its own voltage, never apply voltage and never measure resistance of the sensor circuit. To measure voltage signals, use an analog voltmeter with a high input impedance, at least 10 megohms. Remember, a digital voltmeter will average a changing voltage." End Quote

Measuring the O2 sensor voltage at the computer will give you a good idea of how well they are working. You'll have to pull the passenger side kick panel off to gain access to the computer connector. Remove the plastic wiring cover to get to the back side of the wiring. Use a safety pin or paper clip to probe the connections from the rear. The computer pins are 29 (LH O2 with a dark green/pink wire) and 43 (RH O2 with a dark blue/pink wire). Use the ground next to the computer to ground the voltmeter.

Most of the common multimeters have a resistance scale. Be sure the O2 sensors are disconnected and measure the resistance from the O2 sensor body harness to the pins on the computer.

Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter. Do not attempt to measure the resistance of the O2 sensors, it may damage them.

The O2 sensor ground (orange wire with a ring terminal on it) is in the wiring harness for the fuel injection wiring. I grounded mine to one of the intake manifold bolts

Code 63 - Throttle Position Sensor (TPS) signal too low TPS. Vref missing (5 volt reference voltage supplied by the computer), bad connections or damaged wiring, TPS sensor failed, TPS sensor way out of adjustment. Use a DVM to check for 5 volts on the Orange wire. If it is missing, look for +5 volts at the Orange wire on the EGR or MAP sensor located on the firewall near the center of the car.
Try this... Currently there is some dispute about setting it at .99 volts being worth the effort, but anything less is probably OK. All you need is less than 1.0 volt at idle and more than 4.25 at Wide Open Throttle (WOT). You'll need a Digital Voltmeter (DVM) to do the job.

Here’s a TPS tip I got from NoGo50…

When you installed the sensor make sure you place it on the peg right and then tighten it down properly. Loosen the back screw a tiny bit so the sensor can pivot and loosen the front screw enough so you can move it just a little in very small increments. I wouldn’t try to adjust it using marks. Set it at .97v-.99v, the closer to .99v the better. Just don’t go over .99, or you upset the fuel calibration and idle quality will suffer.

(copied from MustangMax, Glendale AZ)

1. Always adjust the TPS and Idle with the engine at operating temp. Dive it around for a bit if you can and get it nice and warm.

2. When you probe the leads of the TPS, do not use an engine ground, put the ground probe into the lead of the TPS. You should be connecting both meter probes to the TPS and not one to the TPS and the other to ground.

3. Always reset the computer whenever you adjust the TPS or clean/change any sensors. I just pull the battery lead for 10 minutes.

4. Check the procedure for your year, on my 90 I have to turn the idle screw until it just touches the tab, then insert a .010 feeler gauge and give it about one more turn. Then you adjust the TPS voltage to .98v, reset the computer. Start it up, if the idle is to low then turn the screw in until it is just right, then readjust the TPS voltage to .98v and reset the computer and start it up. The key is to adjust the TPS voltage and reset the computer whenever the idle screw is changed.

Code 67 - clutch not depressed (5 speed) or car not in neutral or park (auto) or A/C in On position when codes where dumped. Possible neutral safety switch or wiring problem. This code may prevent you from running the Key On Engine On tests. You can generally ignore this code, since it has no effect on engine performance.

Code 81 – Secondary Air Injection Diverter Solenoid failure AM2. The solenoid valve located on the back side of the passenger side wheel well is not functional. Possible bad wiring, bad connections, missing or defective solenoid valve. Check the solenoid valve for +12 volts at the Red wire and look for the Lt Green/Black wire to switch from +12 volts to 1 volt or less. The computer controls the valve by providing a ground path on the LT Green/Black wire for the solenoid valve.

See http://www.veryuseful.com/mustang/tech/engine/images/88Stang5.0Vacuum.gif for help on the vacuum line plumbing.

Remove the large rubber hoses from the rear of the aft vacuum control valve. One hose goes to the pipe to the back of the heads. The other hose goes to the pipe that goes to the cat converters. Start the engine and apply vacuum (steal a line from the manifold somewhere) the airflow out of the valve should switch from one outlet to the other. If it doesn't then the vacuum control valve is bad.

With the engine running, stick a safety pin in the LT Green/Black wire for the solenoid valve & ground it. That should turn the solenoid on and cause air to flow out the port that goes to the pipe connected to the cats. If it doesn't, the valve is bad. If it does cause the airflow to switch, the computer or wiring going to the computer is not signaling the solenoid valve to open.

Code 82 – Secondary Air Injection Diverter Solenoid failure AM1. The dump valve air diverter valve (front vacuum operated valve) isn’t working on the Thermactor Air System (smog pump). Look for broken or missing vacuum lines on the solenoid valve to the diverter valve Check the solenoid valve for +12 volts at the Red wire and look for the Red/White wire to switch from +12 volts to 1 volt or less. The computer controls the valve by providing a ground path on the Red/White wire for the solenoid valve.

Code 85 - CANP solenoid - The Carbon Canister solenoid is inoperative. Check vacuum lines for leaks and cracks. Check electrical wiring for loose connections, damaged wiring and insulation. Check solenoid valve operation by grounding the gray/yellow wire to the solenoid and blowing through it.
The computer provides the ground for the solenoid. The red wire to the solenoid is always energized any time the ignition switch is in the run position.

Code 87 – fuel pump primary circuit failure. The fuel pump lost power while the engine was running. Check fuel pump relay, check inertia switch, wiring to/from inertia switch, red wire going to inertia switch for +12volts. Check the other side of inertia switch for +12 volts.

To help troubleshoot the 87 code, follow this link for a wiring diagram for 89-93 cars [urlhttp://www.autozone.com/servlet/UiBroker?ForwardPage=az/cds/en_us/0900823d/80/19/59/5a/0900823d8019595a.jsp [/url]

For 79-88 cars use, http://www.autozone.com/servlet/UiB..._us/0900823d/80/16/71/3c/0900823d8016713c.jsp

Code 93 - Throttle linkage binding or bad ISC motor. ISC HO2S not reading Fuel control. The IAB or IAC isn’t controlling the idle. See code 12 if it appears. Clean the IAB and electrical contacts, set the idle speed and TPS.

Try this... Currently there is some dispute about setting it at .99 volts but anything less is probably OK. All you need is less than 1.0 volt at idle and more than 4.25 at Wide Open Throttle (WOT). You'll need a Digital Voltmeter (DVM) to do the job.

The Orange/White wire is the VREF 5 volts from the computer. You use the Dark Green/Lt green wire (TPS signal) and the Black/White wire (TPS ground) to set the TPS

Here’s a TPS tip I got from NoGo50

When you installed the sensor make sure you place it on the peg right and then tighten it down properly. Loosen the back screw a tiny bit so the sensor can pivot and loosen the front screw enough so you can move it just a little in very small increments. I wouldn’t try to adjust it using marks. Set it at .97v-.99v, the closer to .99v the better.

(copied from MustangMax, Glendale AZ)

1. Always adjust the TPS and Idle with the engine at operating temp. Dive it around for a bit if you can and get it nice and warm.

2. When you probe the leads of the TPS, do not use an engine ground, put the ground probe into the lead of the TPS. You should be connecting both meter probes to the TPS and not one to the TPS and the other to ground.

3. Always reset the computer whenever you adjust the TPS or clean/change any sensors. I just pull the battery lead for 10 minutes.

4. Check the procedure for your year, on my 90 I have to turn the idle screw until it just touches the tab, then insert a .010 feeler gauge and give it about one more turn. Then you adjust the TPS voltage to .98v, reset the computer. Start it up, if the idle is to low then turn the screw in until it is just right, then readjust the TPS voltage to .98v and reset the computer and start it up. The key is to adjust the TPS voltage and reset the computer whenever the idle screw is changed.

Fix the code 14 first, then fix the 41/91 codes. You'll have approximately $75 for the code 14 - new distributor unless you do it the hard way and replace the pip sensor. The code 41/91 are two new O2 sensors at $45 each unless you get lucky and find that it is bad wiring or a vacuum leak that is easy to fix. Estimate $165-$175 (your cost) for parts and about 2 hours time to repair if you just swap the distributor.

The combination of codes 31 & 63 tells that you may have a wiring problem. Look for +5 volts on the orange wire - no 5 volts, look at the MAP/Baro sensor for 5 volts on the orange wire there. If the MAP/Baro sensor has 5 volts, then the salt & pepper shaker wiring is suspect. If the MAP/Baro sensor does not have 5 volts, then either the computer is bad or you have major wiring problems in the wiring harness. Do not replace the computer before troubleshooting the wiring harness. Computers seldom fail.

The computer uses the tPS signal to help calculate the amount of fuel needed for the current level or RPM.

Here's a book that will get you started with how the Ford electronic engine control or "computer" works.

Ford Fuel Injection & Electronic Engine Control 1988-1993 by Charles Probst :ISBN 0-8376-0301-3.

It's about $20 from Borders.com see http://www.amazon.com/ . Select boo...very good, and I found it to be very helpful.

If the TPS was reading high (phase shifted right) the computer should have thought you were deeper into the pedal, and richened up the mixture. You could also possibly go into WOT trim sooner. Then again, it should have baselined out anyhow (been a non-issue).

The TPS is also pretty critical for on and off throttle transitions and can be a spot where it shows it was not up to par (though not necessarily in a simple phase shift reading).

You can try and slot one of the mounting bosses for the new TPS to get your baseline reading down. This is, as always, a source of great debate. Bottom line is I dont think it hurts anything to fine tune it, so go for it if you like (I dont get as passionate about not adjusting it as one of Jrichker's contemporaries. ).

Good luck.

bdazzgt said:

ok so the tps could of caused the pinging or not? i am confused,( it doesnt take much) and what happens if i dont get the tps adjusted for a few days any negative effects?

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I just re-read the thread. I thought (based upon what I was quoting from you in that last post) that your TPS reading was high. But your code was for low voltage, right? If you were reading lower than you should have across the board (and below the adaptive limit, at that), then the TPS reading would be on the lean side, not rich. If this was the case, I apologize - I must have gotten confused in what was being said.

bdazzgt said:

Can you elaborate on this more so i can fully understand this? This is what i got from it if the tps was high it would dumped more fuel in sooner, causing this to not be a problem. The second statement is a little confusing can you explain this in terms for dummies, i wanna learns how this stuff works and i dont have that book jricker recommended yet.

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If the TPS is working properly, but set on the high side, two things should happen. Either the computer will adapt and it wont matter, or the puter cant adapt and it spits a code. You got the code (but it was a low-limit code, IIRC). If the TPS is high (which you mentioned), it would be telling the computer that your are desiring more power from the engine than you really are. The TPS just relates to the computer the relative throttle position (how far your foot is in the pedal) since other sensory input can be delayed or difficult to interpret quickly if you are on and off the throttle very quickly and a lot.

As always, if you read something different from JRichker, go with his info. His long posts covered some of this stuff (apologies for echoing some of your thoughts JRichker). I find that I have to read his posts several times at different times to absorb it all (or try).

Good luck.