How to set timing on a 1994 Fleetwood Flair Chevy 7.4L Gas

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Mark97213

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Portland OR
Greetings. I can't locate the disconnect wire for the auto timing advance. In order to set the timing on this Chevrolet 7.4L Gas motor, the auto timing advance or EST wire needs to be disconnected but I cannot locate this wire within obvious sight anyway. On GM passenger vehicles for this year, the wire connector is within the firewall harness and is usually fairly easy to locate but on the Motor home I am unable to locate it and it has to have one. Does anyone have an idea where this disconnect is located?
 

Pedro Dog

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I would do a static timing adjustment first and then put a timing light on. Once you got the static timing set start the engine and with the light adjust the timing to the dynamic setting. I usually use a vacuum gauge to set the timing so to eliminate engine wear. Adjust timing for the highest vacuum reading you can get at normal idle RPMs.
 

udidwht

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HB, CA. - Renton-Highlands, WA. - Fujieda Japan
Greetings. I can't locate the disconnect wire for the auto timing advance. In order to set the timing on this Chevrolet 7.4L Gas motor, the auto timing advance or EST wire needs to be disconnected but I cannot locate this wire within obvious sight anyway. On GM passenger vehicles for this year, the wire connector is within the firewall harness and is usually fairly easy to locate but on the Motor home I am unable to locate it and it has to have one. Does anyone have an idea where this disconnect is located?
It will be very close to the distributor bottom side.

Once set at 4*BTDC note what the timing is when the EST is connected back up. Will be 15-16. This way if you do remove or set the timing again in the future you can use your scan gauge (if you have one).
 
Last edited:

Mark97213

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Portland OR
You're welcome. You may have to use the timing indicator on the lower side of the pulley. Hook your inductive to #5 wire. Let us know what your end result is.
Well, you beat me to it.... that's exactly what i was going to ask. The upper Timing plate is visible through a spot on the water pump but there's no way you can see the HB mark reading on the timing plate. So, the lower one is perfect for timing but that was my question....the inductive pick up goes on #5 instead of on #1? Thank you for that. Timing by yourself on one of these behemoths is time consuming...I'm sure you know why. I Fired it up, crawled under there, grabbed the timing light and then, there are that moment I said... "wait, this isn't going to work." ;)
 

viceprice

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Maine
I bought one at AutoZone over the counter - about $130 that I use to monitor water temp primarily - much more accurate than the factory guage. I also found the speed (mph) was more accurate than my speedometer. I have it mounted with Velcro right behind the steering wheel and in front if the guage cluster. We have the 7.4L in our TV.
 

viceprice

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I meant to add the one I bought is called ScanGuage . Has its own display. No phone app I am aware of on this particular unit.
 

Pedro Dog

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I think this is an OBD1 vehicle so scan tool may not support it. OBD1 tools are not very common outside of repair shops.

On my older OBD1 truck, I used to read codes by flashing lights from the dashboard panel after jumping two pins

1664735302289.png

When you find the adapter connector, use a jumper wire (see red wire above) and connect terminals A and B. Next turn your key on but don't start. Watch your check engine flash the code/s.

EXAMPLE: CODE 12: one long flash and two short flashes, CODE 13: one long flash and 3 short flashes.

Note: code 12 is usually the first code you get and just ignore it.Watch the code after code 12, that's what you need.

GM common codes for OBD1 (for vehicles made before 1995)
12 System normal
13 oxygen sensor circuit open
14 coolant sensor high resistance or shorted
15 coolant sensor circuit low or open
16 direct ignition system (DIS) fault in circuit
17 cam position sensor fault
18 crank or cam sensor error
19 crank sensor circuit fault
21 tps sensor out of range
22 tps sensor signal voltage low
23 intake air temp sensor out of range, low
24 vehicle speed (vss) sensor circuit fault
25 air temp sensor sensor out of range, high
26 quad-driver module (computer) circuit #1 fault
27 quad-driver module (computer) 2nd gear circuit
28 quad-driver module (computer) circuit #2 fault
29 quad driver module (computer) 4th gear circuit
31 cam position sensor fault
32 egr circuit fault
33 map sensor signal out of range, high
34 map sensor signal out of range, low
35 idle air control sensor circuit fault
36 ignition system circuit error
38 brake input circuit fault
39 clutch input circuit fault
41 cam sensor circuit fault, igntion control circuit fault
42 electronic spark timing (EST) circuit grounded
43 knock sensor
or electronic spark control circuit fault
44 oxygen sensor lean exhaust
45 oxygen sensor rich exhaust
46 pass-key II circuit or ps.pressure switch circuit fault
47 pcm-bcm data circuit
48 misfire diagnosis
51 calibration error, mem-cal, ecm or eeprom failure
52 engine oil temperature circuit, low temperature indicated
53 battery voltage error or egr or pass-key II circuit
54 egr system failure or fuel pump circuit low voltage
55 a/d converter error or pcm not grounded or lean fuel or frounded reference voltage
56 quad-driver module #2 circuit
57 boost control problem
58 vehicle anti-theft system fuel enable circuit
61 a/c system performance or degraded oxygen sensor signal
62 engine oil temperature high temperature indicated
63 oxygen sensor right side circuit open or map sensor out of range
64 oxygen sensor right side lean exhaust indicated
65 oxygen sensor right side rich exhaust indicated
66 a/c pressure sensor circuit low pressure
67 a/c pressure sensor circuit or a/c clutch circuit failure
68 a/c compressor relay circuit failure
69 a/c clutch circuit head pressure high
70 a/c refrigerant pressure circuit high
71 a/c evaporator temperature sensor circuit low
72 gear selector switch circuit
73 a/c evaporator temperature circuit high
75 digital egr #1 solenoid error
76 digital egr #2 solenoid error
77 digital egr #3 solenoid error
79 vehicle speed sensor (vss) circuit signal high
80 vehicle speed sensor (vss) circuit signal low
81 brake input circuit fault
82 ignition control (IC) 3X signal error
85 prom error
86 analog/digital ecm error
87 eeprom error
99 power management
 

Pedro Dog

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You are right about OBD1 code readers being available.

OBD1 tools are not very common outside of repair shops.

What I should have said is that OBD1 "tools that may support the live data monitoring" are not very common outside of repair shops.

This device when connected, puts a jumper in the same pins as you would manually. See step 3 in the instructions below.

It blinks the same information and uses the vehicle dashboard. See step 5 in the instructions below.

It does not record live data and will not support setting the timing of the engine.

from the manual,

2.3 RETRIEVING SERVICE CODES
• Always observe safety precautions before and during the testing process.
• Fix any known mechanical problems before this test.
• Have pencil and paper handy.
1. Turn off ignition.
2. Connect the Code Reader to the vehicle test connector.
NOTE: The Code Reader only fits into the connector one way.
3. Set Selector Switch to ECM A-B position.
4. Turn on ignition. DO NOT START THE ENGINE.
5. Read codes from the "Check Engine" or "Service Engine Soon" light (from the "Shift to D2" light - 1991 and 1992 models or the "Temperature" indicator light - 1993 and subsequent - for Saturn Electronic Transmission codes) on your vehicle's instrument panel. Be sure to write the codes down.
NOTE: If the light does not blink, refer to your vehicle's service manual for information on checking the circuitry.
• All codes are two digits.
• Each code is transmitted three times before the next code is sent.
• Code sets will begin with Code 12 ("System Pass") even if fault codes are present.
• The codes will continue to be sent as long as the ignition is on and the Code Reader is connected.
• Count blinks to get the service codes:
 

Pedro Dog

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Location
South Shores, CA
It looks like a nice tool. So it displays real time data? One can monitor timing as it is adjusted? If so, then that's what the OP needs.
 

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