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Rough idle and running very rich

101K views 13 replies 8 participants last post by  JKossarides  
#1 ·
The other day i parked my F150(302 EFI), and went to start it up about 3-4 hrs later and it was running like crap. Its hard to start, runs very rich, has a rough idle, smells like gas when i start it up and take off from a light, and under a lot of load it kinda bucks like its missing bad. At first i thought it was water coming through the scoops in the hood i just put on got the distributor wet since it rained heavy that day, so i popped it open and it was dry. I added some fuel treatment and pulled off a few spark plug wires to see if any cylinders were not contributing. 1 or 2 seemed to be doing very little so i figured id change the pluggs and wires. Didnt change. Anyone know what else it might be?
 
#2 ·
It probably couldn't hurt to check the timing. I had similar issues when the timing was off.
 
owns 1989 Ford Bronco Xlt
#5 ·
Yea but i only got
52- Power Steering Pressure Switch/circuit open - PSP
29- Vehicle Speed Sensor problem - VSS
33- ALL - EGR did not open/ respond during test or if memory code, did not open intermittently - EVP EVR PFE
41- System lean - Fuel control

The 29, 33, and 41 are the continuous Memory codes
 
#7 ·
There are several sensors that work in relation to each other at "cold start" and normal operation as fuel managers so X2 on pulling codes for initial diagnosis.

Sensors are:

IAC = idle air control, located on the right side of the throttle body can be cleaned by removing it using TB cleaner in the (bottom) valve part only, repalce gaste if necessary to avoid vaccum leak.

TPS = throttle position sensor, located on the bottom of the throttle body is for "blade angle/air induction" and is voltage driven.

ECT = engine cooling temp sensor, usually located in an "octagonal tree" that's threaded into the lower intake manifold along with a lower TB coolng tube hose and in-line heater hose on a long tube coming in form the passenger side underneath the FI plenum.

O2 = oxygen sensor, 1 or more usually located in the passenger side exhaust header

Since you got a code on it, EGR = exhaust return gas sensor located on top of the EGR valve has a vaccum line on it.

There are back probing procedures for all of these in the Haynes Manual so you may have to check them to eliminate them as suspects AND X2 for disconnecting the battery for 20-30 minutes and either turning the lights on or pressing the brake pedal momentarily will purge any remaining power so when reconnecting, settings should default back to OEM spec's and see if that helps.


Good Luck ~ :thumbup
 
#8 ·
I just went to start it and it wouldnt turn over so i pulled the bad plug and gas poured out. So im pretty sure it a leaky/ stuck open injector which would explain a lot
 
#9 ·
yo,
Ford went from two-digit to three-digit EEC IV Self-Test codes in 1991 to service the increasing number of service codes required to support various government On-Board Diagnostic (OBD) regulations. The phase-in from two-digit to three-digit codes started in the 1991 model year
So, you should get 3 digit codes;
And Fireguy needs to include the KOER portion to his KOEO site or a hot link soon, bec too many just do the KOEO portion.

so, a Self Test by BroncoJoe19
An assistant to write the info is helpful

heat the engine up; idle until temp gauge is in normal range you usually see
and when it warms up; shift thru all gears incl Reverse anyway.

Then turn off all accessories/lights, etc.

Make sure A/C is off and transmission is in Park (automatic)

Do Key On Engine Off (KOEO) portion first.

engine temperature must be over 50°F for the KOEO Test & More than than 180°F for da KOER portion.

Look Codes up in my broncolinks.com site using the new Search function if in a hurry today.

And Post em here according to
KOEO
& KOER


The EGR Valve Position (EVP) Sensor used exclusively by Ford, can be the cause of driveability problems without ever setting any trouble codes. The relationship between the EVP sensor and the EGR valve is important to understand. Either one being out of spec can cause similar symptoms. Understanding this relationship will help you to diagnose uncoded driveability problems like stumbles, hesitations, rough idles and stalling..." read more by rla2005 (Randy) & miesk5 at FSB


DTC 31, 32. 33. 34. 35. 38 or 84 - EGR Valve Position (EVP) Sensor & EGR Vacuum Regulator Solenoid (EVR) Testing
Source: by Dustin S (Dustball, Mellow Yellow, Mr. Laser Boy) at ylobronc.users.superford.org

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as I mentioned in another thread here; In place of the breakout box, go to the EEC connector pin instead; Substitute EEC connector pin Number for breakout box number

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EEC Connector Pin Diagram
Source: by Fireguy50 (Ryan M) at http://web.archive.org/web/20131229163930/http://oldfuelinjection.com/images/eec04.gif
EEC Connector Pin LEGEND Bronco & Ford Truck & Van: 4.9, 460, 5.0, 5.8; miesk5 Note, see his Connector Pin Diagram Link above)
Source: by Ryan M (Fireguy50) at http://web.archive.org/web/20131029020805/http://oldfuelinjection.com/truckpinouts.html

Testing; "...Using the Haynes manual's procedures, you should be able to back-probe the EVP line and ascertain whether the EVP voltage is correct. It should be below 0.67V @ zero vacuum on the EGR, slowly increasing with applied vacuum from a hand pump. DO NOT apply more than 10 in-Hg to the valve..."
Source: by SigEpBlue (Steve) at http://fullsizebronco.com/forum/showthread.php?t=163513

DTC 33 & 34 "...DTC 33 is triggered when the EVP sensor is not closing... To prevent the EGR valve from opening when the engine is cold, the vacuum line to the EGR valve may be connected to a a computer-controlled solenoid. Vacuum is not allowed to pass to the valve until the engine is warm. EGR isn't needed when the engine is cold, only when it is warm and under load. Any of these codes could indicate a faulty EGR valve as well. as well as a problem in the ...vacuum solenoids. code 33 is triggered when the EVP sensor is not closing, Any of these codes could indicate a faulty EGR valve as well as a problem in the EGRC or EGRV vacuum solenoids. Other codes include a code 83 (EGRC circuit fault) and code 84 (EGRV circuit fault). Both indicate an electrical problem in one of the solenoid circuits. The solenoids should have between 30 and 70 ohms resistance..." Miesk5 note; da TAB & TAD ; so repair those vac lines 1st

DTC 33 is triggered when the EVP sensor is not closing; so EZiest & cheapest checks are to inspect & repair/replace repair any bad vac lines. for a <$ vac line test; I pull em off and use the straw sucking test; one finger over one end; includes EVP testing & Links
Source: by miesk5

Testing & Operation; "...The EGR Valve Position (EVP) sensor monitors the position of the EGR valve pintle. The EVP sensor converts the mechanical movement of the pintle into an electrical voltage signal which is relayed to the PCM. The EVP sensor is a linear potentiometer in which resistance varies with the EGR valve pintle movement.Voltage is fed to the EVP by the signal return circuit. As the EGR is opened the EVP directs more voltage to the EEC and less down the voltage reference circuit. The EVP sensor provides the PCM with information on EGR flow and EGR system failures. The EVP should read between 0.24 and 0.67volts at idle with a closed EGR valve..." read more
Source: by Ryan M (Fireguy50) at http://fordfuelinjection.com/index.php?p=35

Testing & Operation in a 94; "...There is no PFE on your truck. This is an "either/or" situation with some engines using the PFE sensor and others using the EVP sensor. The Pressure Feedback EGR sensor measures back-pressure in the exhaust system and sends this info to the PCM. In the case of the EVP sensor, the information is sent in the way of sensing the actual position of the EGR valve. 327 indicates the voltage in the EVP circuit was lower than it should EVER be. However, 337 indicates that the voltage coming back to the PCM is too high. These conflicting codes need to be verified. You may have wiring damage with this situation. EVP sensor should have three wires running to it. BROWN/WHITE (pin1), GREY/RED (pin2), BROWN/LT. GREEN (pin3). The GREY/RED is always the signal return. For two-pin sensors the PCM uses the voltage coming back down this wire for information. For three-pin sensors the PCM uses both this and the third pin (in the case of the EVP sensor, the BROWN/LT. GREEN wire) as a comparison voltage to the signal return voltage in the GREY/RED wire. Pin 46 of the PCM is the signal return terminal. The PCM assumes the necessary voltage drop through the wiring harness and takes the voltage from the third (BROWN/LT. GREEN) pin as a comparison. The difference is calculated and the PCM makes adjustments accordingly. The voltage at pin 46 of the PCM should be very close to the same voltage as found at pin 26 or slightly lower. To check that the VREF (reference voltage) generated by the PCM power supply is good, meter between pin 26 of the PCM and a good frame ground. Double check the wiring harness TO the EVP sensor by checking for the same voltage at the BROWN/WHITE wire in the EVP connector in the wiring harness. If you have a good VREF voltage (5VDC approx.) then jump the BROWN/WHITE wire to the BROWN/LT. GREEN wire and check the voltage at pin 27 of the PCM. If you still have good VREF voltage, the problem does NOT lie in the wiring harness. You can do the "wiggle" test on the harness to make sure there are no weak or loose connections between the sensor connector and the PCM. To test the EVP sensor itself, probe the pins that connect to the aforementioned wires and run the test by applying vacuum as described in my previous post. As mentioned, the resistance should change smoothly as the vacuum is slowly released. If it does not, the EVP is bad. Note: Only run this test with the EVP sensor disconnected from the wiring harness or your readings will be tainted by the electronics in the PCM. One thing to note here is that the VREF feed for the EVP sensor splits off to both the TP (throttle position) sensor and the MAP (manifold absolute pressure) sensor somewhere in the main harness between the firewall and the individual sensors. You might do well the check for damaged wires at all of these sensors just in case the harness is damaged and shorting at one of the other sensors being fed VREF..."
Source: by greystreak92


Operation & Testing; "...The EGR Valve Position (EVP) Sensor used exclusively by Ford, can be the cause of driveability problems without ever setting any trouble codes. The relationship between the EVP sensor and the EGR valve is important to understand. Either one being out of spec can cause similar symptoms. Understanding this relationship will help you to diagnose uncoded driveability problems like stumbles, hesitations, rough idles and stalling. First, remember that EGR valves are designed to reduce harmful NOx emissions that may occur when cylinder peak combustion temperatures reach 2500 degrees Fahrenheit. At this temperature, Nitrogen (N), which makes up 78% of the intake air, will combine with Oxygen (O), which makes up 21% of the intake air, in various ratios. The letter "x" represents these various combinations. When NOx enters the atmosphere it unites with hydrocarbons with the help of the sun and smog forms. Whenever the EGR valve allows exhaust to re-enter the intake manifold it displaces good burnable air/fuel. This cools the combustion but also reduces the power that the cylinders produce. Therefore, we must make sure that this doesn't happen at the wrong time. The wrong times are: ) During cold engine operation. 2) During engine idle. 3) During high power demands. EGR operation during any of these conditions will cause hesitations, rough idle or engine stalling. Today, EGR activity is better controlled by computer operated solenoids and backpressure sensing valves. This greatly overcame the driveability problems of the early EGR systems of the 70's. The EEC IV system uses the EVP sensor to advance timing and, therefore, help burn the mixture better during EGR flow. The EVP sensor measures the EGR valve position in the same way that the Throttle Position Sensor measures throttle position. As a matter of fact, these electrical circuits work in very much the same way. They both use three wires; 1) 5 volt reference 2) ground and 3) sensor output to the computer. They both send a low voltage at closed position and a high voltage at maximum opening. The EVP's closed voltage depends on the EGR's closed position and the EVP's maximum voltage depends on the EGR's position when it is at maximum travel. Any position in between minimum and maximum depends on vacuum signal strength and the EGR return spring resistance to the vacuum signal. So, different voltages will be produced by different vacuum signals. The chart below shows you the relationship between the vacuum signal strength in inches of mercury ("Hg) and the voltages that result from the EVP sensor. Remember that this chart applies to EGR valves that have good return springs. NOTE: Allow +/- .2 volts for all specifications. Now, the problem with this chart is that it doesn't tell you how to move the valve to the opening percentages. The missing information is that Ford EGR valves will open 100% at 8 "Hg. Therefore, 50% opening will be obtained by creating 4 "Hg, etc. Now that you know this, you can open the EGR valve using a vacuum pump and watch the voltage on your digital voltmeter with the key on engine off. If you find that the voltage rises more than the chart allows, you probably found the cause for the stumble or hesitation. The EGR valve spring has become weak and it responds too quickly. But, because it is still within the allowed voltage range, there is no trouble code stored. Keep in mind that the EVP Sensor could also be out of calibration or stuck. So when you disassemble the EVP Sensor from the EGR valve you must determine which was at fault. Also be careful to reassemble them with a new "O" ring. This will ensure that a vacuum leak doesn't occur..." See Diagram
Source: by KEM Auto Parts kemparts.com™ via web.archive.org


Wiring Diagram in a 94 from EVTM

Source: by Mikey350 at SuperMotors.net

Vacuum Pump; AutoZone has a Hand Operated pump in their Loan-A-Tool® service, part number OEM27010 with a deposit; "Gauge reads 0 to 30 inches of mercury. All aluminum construction with reverse pistol grip for easy one-handed operation. One 24 inch piece of clear plastic tubing included with pump. When you're through, just bring it back, and we'll refund the deposit..."
Source: by autozone.com

I'll post this part up noe on case I need to re-load.
 
#11 ·
29 (c): VSS (Vehicle Speed Sensor) voltage too low.
DTC 29 & 452 Erratic Harsh Shift; PSOM Operates Correctly; "...Continuous Memory DTC 29 indicates that during the last 80 warm-up cycles, the PCM detected an error in the PSOM output signal. DTC 452 indicates the PCM detected an error in the PSOM output signal during the last 40 warm-up cycles. his procedure EXACTLY, from the Ford TSP/PCED..." READ MORE
Source: by SigEpBlue (Steve) at http://fullsizebronco.com/forum/showthread.php?t=161210&highlight=psom

52 (o): PSPS (Power Steering Pressure Switch) circuit open. Suspect PSPS, harness. (r): PSPS did not change states.
On vehicles equipped with the Brake On/Off (BOO) circuit, the brake pedal MUST be depressed and released AFTER the ID code.

· On vehicles equipped with the Power Steering Pressure (PSP) switch, within 1 to 2 seconds after the ID code, the steering wheel must be turned at least one-half turn and released.
· On vehicles equipped with E4OD transmission, the Transmission Control Switch (TCS) must be cycled after the ID code.

· The Dynamic Response code is a single pulse (or a 10 code on the STAR Tester) that occurs 6-20 seconds after the engine running identification code. (See Code Output Format in this section.)

· When/if the Dynamic Response code occurs, perform a brief wide open throttle.



DTC 41, 42, 91, 92, 136, 137,139, 144, 171, 172, 173, 175, 176, 177 & some Possible Causes for Rich & Lean HEGO The engine temperature must be greater than 50°F (10°C) to pass the KOEO Self-Test and greater than 180°F (82°C) to pass the KOER Self-Test. To accomplish this, the engine should be at normal operating temperature
Source: by Ryan M (Fireguy50) at fordfuelinjection.com

41 (r): EGO/HO2S oxygen sensor voltage always below "lean" on bank #1. (c*): No EGO sensor rich/lean transitions detected, bank #1. EGO read lean for more than 15 seconds while in closed loop.

DTC 41, 42, 85 OR THREE DIGIT CODES 171, 172, 173, 179, 181, 182, 183 & 565 are received , Check for proper HEGO Ground; in Catalytic Converter Diagnosis TSB 91-12-11 for 86-91 Bronco, F Series, & Econoline
Source: by Ford via Steve83