Engine Car Wont Rev Past 4/4.5k

Trust me a bad ECT sensor will cause your car to run real rich or real lean once the engine is warm. And sometimes it will not even send a code and your car will run like crap.

omarimoe said:

Well I'll give the guy a little more time to mess with the car and see what all he finds I guess im just impatient lol. I had the car for like 2 months now trying to figure this out and cant so i cant expect him to find the problem in 20 mins. This is the only car I have ever given up on and farmed out for someone els to look at so im a little out of my element.

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If the don't have the ECT temp to voltage map, they will never find a marginal ECT....


Code 51 Engine Coolant Temperature (ECT) sensor signal is/was too high -
Possible bad ECT sensor, or wiring. Possible missing signal ground – black/wire wire broken or bad connection. With the power off, measure the resistance between the black/white wire and battery ground. You should see less than 1 ohm. Check the same black /white wire on the TPS and MAP sensor. More than 1 ohm there and the wire is probably broken in the harness between the engine and the computer. The 10 pin connectors pass the black/white wire back to the computer, and can cause problems.

The ECT sensor is not the same as the temp sender for the temp gauge. It is located in the front part of the tubing that feeds coolant to the heater. It has two wires connected to it.

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Voltages may be measured across the ECT by probing the connector from the rear.
Use care in doing it so that you don't damage the wiring or connector.

50 degrees F = 3.52 v
68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61
212 degrees F = .47 v
230 degrees F = .36 v
248 degrees F = .28 v

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.

50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms
212 degrees F = 2.07 K ohms
230 degrees F = 1.55 K ohms
248 degrees F = 1.18 k ohms

Diagram courtesy of Tmoss & Stang&2birds



See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/

http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

omarimoe said:

So to make sure im understanding correctly the ECT, TPS, and, MAP all share a common ground/ black/white wire? If so it would make sense if I have a broken wire or bad connection at the 10 pins somewhere because I have that TPS code. Now I wish I still had the car at my house so i could check right now lol. Is there any company that makes a plug and play repro harness? Mine is old and has had its number of hacked stuff anyway. I know late model has the injector harness and 02 harnesses but does anyone make a complete one?

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The engine mounted sensors and MAP all share the black/white wire (pin 46 on the computer) as a common signal ground. The 10 pin connectors can sometimes cause flaky problems that are hard to find.




See the graphic for the 10 pin connector circuit layout.

It's rare these things fail when new out of the box. I'd trade it out with Late Model, they have great customer service.

Tank is probably 20+ years old and the inside might look like the hanger, I vote for a new gas tank and hanger

Bring it to a local radiator shop and see if they can hot tank it for you.

omarimoe said:

been there done that they want $20 less than i could get a brand new tank for so i just cleaned it the last time around and thought i got it pretty clean but apparently i was mistaken. anyone have the stangnet discount codes for late model and American muscle im trying to decide where i want to order stuff and late model takes minimum 6 days to get me parts but American muscle can get me stuff in about 2.

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email them for the code and they will send it to you . They both price match