21: One of the o2 sensors is out of whack
22:Coolant temp sensor voltage is too low
42: asd relay
42: fuel pump relay

Now for the questions! I got the cel for most of these today, which leads to the o2 question. I hooked my a/f gauge up yesterday after installing a new coolant temp sensor. The wire for the gauge is bigger than the o2 wire itself. Will the larger wire pull too much voltage away from the sensors readings in the ecu? Next, the coolant temp sensor is brand spankin new, but i did check the wiring out yesterday with my voltmeter. The plug itself with the key in the on position reads 8.8 volts, shouldnt it be closer to 12? Im not worried about the asd and fuel pump relays, i knew they were on the way out, but, could they hurt performace at all with the cel? Any help is appreciated

I think the ECU's takes the coolant sensors voltage into an account when working on fuel trims so I would think that it makes a difference.

but like i asked, is 8.8 volts at the plug bad? Should it be 12 instead?

I tried searching around for the voltage req's for that sensor but didn't find anything. Dino has the service manual's in his sig but I can't view PDF's and I don't think they have the electrical stuff in there. Sorry, bro.

yeah i cant find the information either, im burning up my buddylist too

the ASD relay is what suppies voltage to the sensors including the cooling sensor. With the code you have for the sensor you should not have replaced it. The cooling sensor should get 12volts. If the ASD relay has tracking or flashing inside it on its contacts and is not allowing the full 12volts pass then it will cause your coolant sensor code (low voltage code), may affect the o2 sensor and fuel relay...i am not shure i willhave to check that the o2 heater gets 12+ from the ASD. Troubleshoot the larges thing first and work your way to the smaller. Check the voltage comming out of the ASD for 12+. if your getting a full 12+ then you have voltage drop in the harnes...ie a corroded or bad connection creating resistance and voltage loss.

you did not get a cooling sensor out of range or failure code so you should not have replaced it.

Terry

96 Eagle talon ESI
Star Stage II - Boost/oil/EGT gauges

97 Eclipse
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thanks for the information, i know exactly where to start now. Where in the haynes manual would i find specs for the asd relay?

more information...i tested the relay, its reading 12.5 volts with the key in the on position. After doing corbins relay check(hooked up power and ground and tested continuity, it reads .3 with the positive and negative wires connected and nothing with the negative wire disconnected. Corbins write up says that you should have 0 continuity with power to the relay.

Also, i checked the ohms while the relay was disconnected and it read 76.3, while corbins page says it should be within 35-75 ohms or replace. Good enough reasons to replace?? Could this be causing hesitation?

Originally posted by EclipsedChef
more information...i tested the relay, its reading 12.5 volts with the key in the on position. After doing corbins relay check(hooked up power and ground and tested continuity, it reads .3 with the positive and negative wires connected and nothing with the negative wire disconnected. Corbins write up says that you should have 0 continuity with power to the relay. Also, i checked the ohms while the relay was disconnected and it read 76.3, while corbins page says it should be within 35-75 ohms or replace. Good enough reasons to replace?? Could this be causing hesitation?

eh ok sort of what i was talking about but i am more concerned with voltage drop. The 76.5 Ohm you are reading is the coil inside the Relay, what actually energizes to close the circuit. The other two terminals are the 12+ that is being switched. That is what i am concerned with. one will have 12+ at all times even with the key off and relay disconnected. The other and last terminal is only energized when power is supplied to the coil inside the relay. That is the terminal i want you to test. plug the relay in but leave it off the bracket. Insert your probe to the mulitmeter into the terminal that is switched on and turn the key. The relay will click ofer and the meter should register voltage (as long as the com lead is grounded on the meter). What is that voltage, should be the same as the voltage you are getting at the coolant sensor. Also test for voltage at the cam sensor with key on....should be black wire with green strip. that voltage too should be the same as the voltage at the coolant sensor. If one of these does not match you have a problem in the harness somewhere.

If the sensors match voltage but relay is different...harness problem. If all three are the same and below 12+ then replace the relay. Since the relay coil is 76.5 ohms i would replace only if you are using a fluke/snap on brand meter. Anything other is not industry standard. I say snap on because fluke makes it.

fuel pump relay is not fed from the ASD relay....just looked it up so that may or may not be another problem. Your battery isnt dead is it?
Terry

thank you so much for the info, im going to do everything in the morning and post detail afterwards. If you could, come back and check my info out and explain more, its all coming together now. I actually just got back from a decently long drive through a few curvy mountain roads, and the car responded nicely, only a tiny tiny bit of missfire once i got closer to my home. I did give it one good pull to 6k rpms before i got to my place and it didnt pop once. Im almost at the point where i can call it quits with the missfiring. Thanks again for your help.

just checked over what you said. All three wires on the bottom of the relay tested 12.7 volts with the key off, then 12.5 with the key on. The last wire never changed, it never had voltage. I checked the cam sensor and its getting 8.8 volts, and the coolant temp sensor is getting 4.8 now. So, with that i guess its a wiring harness issue even though ive traced all my wires and never found a cut/slice/burn on any of them. Am i right on these assumptions? Help again!

Yes you are on the right path. the fourth wire doesnt have voltage beecause it gets a neg signal to complete the path for the coil in the relay to switch the 12+ on to the sensors. The wiring goes from the asd relay to the sensors so if you have low voltage at the sensor but 12.5 at the relay then you have a problem in the harness. Since the relay is out of spec on the coil side i would say replace it and double check. I still have a side that hopes for luck, but lets face it, the numbers point to the harness.

Check the harness where it runs along the EGR pipe. It is very common for that harness to contact the pipe and burn through in that area. if you think its a harness problem, that is always the first place to look.

alright, i have a new fuel pump/asd relay portion on the way just to be safe. I got another cel 22 today, as the reading was 4.something earlier today. Ive already torn my wiring harness apart from beggining to end to find shorts and such and the only thing i saw was the wiring at the harness for the coolant sensor was showing. I taped that up nice and tight but i guess its still the problem I'll trace everything out tomorrow and see what i can find. Should i only look at the wiring for the sensors that have low voltage?

Wait a second here.

The Coolant temp sensor, Intake air temp sensor, crank angle, cam angle, TPS, MAP, are all 5V sensors. They should NEVER see 12V+.

c'mon now people, that's common knowledge.

well the cam angle sensor read 8.8 volts, and the coolant sensor read 4.8 i think. Honestly i took the car out yesterday and it ran pretty well. Once i replace the relays i should be set, do you think i should check the harness anyways?