# 87 Stanza fuel too rich



## pappasteve (May 31, 2007)

I was given a 87 Stanza with a CA20E motor. The car just barely ran (sometimes not at all) when I got it. Did some diagnostics checking on it and found that the fuel pressure was too high. The pressure according to the manual should be 30 psi, I was getting 60 psi. I bought a aftermarket adjustable fuel pressure regulator and installed it. The car now runs but is still running to rich. I have checked all the vacuum lines and replaced them as well as checked the vacuum diagram to make sure it was correct. 

What can be checked to find out what is causing the fuel enrichment?


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## bikeman (Dec 26, 2006)

I just sold my 87 Nissan Multi with same motor, it had very low compression on one of the cylinders, that plug was getting quite "wet", maybe do a compression test to make sure you have good compression. My good cylinders were giving me a reading of 190.


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## pappasteve (May 31, 2007)

Yes I have done a compression test and got 150 psi on all 4 cylinders. The manual shows 130 being a min and 170 a max. The motor has 190,000 miles on it so i figured that wasn't too bad for that many miles. Is there any way to check codes or do dianostics on these?


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## bikeman (Dec 26, 2006)

There is no check engine light on the dash in the Stanza wagon, probably the same for the sedan. The computer itself has diagnostic lights that reveal trouble codes. My dealer manual has quite a large section dedicated to diagnostic checks using the onboard computer lights and pulling codes from it, one test was for checking air/fuel mixture. Mine was under the driver's seat, a good shop manual is a must and a great investment. I'm sure you checked but maybe time for new plugs, wires, cap and rotor. I noticed mine used too be hard on the ignition components, this may strengthen your spark and give you a better burn. Of course check your air filter and PCV valve. Also confirm that it is reaching operating temperature and it is out of the "choke" mode, maybe you have a bad Oxygen senser. Although according to the computer the mixture was right on mine and it never failed a smog test, the plugs always seemed to be a little on the fouled side although it never burned oil, also never had great fuel economy. I did do a lot of city, but in comparison I'm now driving a 2000 CR-V auto AWD, heavier with same size motor, more power at 146 hp and it gives me better gas mileage for the same type of driving, my Multi was a FWD


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## pappasteve (May 31, 2007)

I have a Haynes manual but it doesn't have much about the EFI motors. I can actually see black exhaust come from the tail pipe while it is idleing The plugs and wires are in pretty good shape but the rotor and cap are pretty much shot. The air filter is brand new. I know the engine is warmed up due to the electric fan is not coming on and the radiator is very hot. 

Is there a way to test the O2 sensor or other input sensors to see what is causing it to run rich.


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## pappasteve (May 31, 2007)

I tried to check the O2 sensor today. I was getting about 320mv when the motor was cold and once the motor was fully warmed up it got to 920M mv. Once the sensor got to 920 it pretty much stayed there. Is there suppose to be any flucuation in the voltage as it runs? The fan does come on, I let it run a little longer today. 

I also noticed that the motor tends to miss out when you try and rev it up. If you slowly give it gas it will rev up without the miss. The timing cover is not on the motor, I set the timing as close as I could. If it is a little to much advanced could it cause the miss problem. I think I'll go get a new cap and rotor Tues.


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## pappasteve (May 31, 2007)

Is the EAI system only operational when the motor is idleing and cold or anytime when idleing?


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## bikeman (Dec 26, 2006)

Are all the plugs fouled? Try pulling one ignition wire out at a time while it is running and see if there is a noticeable difference in idle. Start with the intake side and then the exhaust, use something to grab boot or you might get a good zap. It could be one of the two wires at a plug that is bad.


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## bikeman (Dec 26, 2006)

I'm just looking at my Stanza Wagon manual and the procedure for checking the exhaust gas sensor with the onboard computer is as follows:
"CHECK FLASHES OF INSPECTION LAMPS ON E.C.U."
1) Warm up engine sufficiently.
2) Make sure that green inspection lamp goes on and off 9 times or more during 10 seconds at 2000 RPM.
Just thinking back to when I replaced my O2 sensor, there was no noticeable difference before or after, I think you have bad wires, I honestly don't think in 1987 the 02's did a hole lot in fuel management.


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## pappasteve (May 31, 2007)

Thanks for all the replies. I'm going to get a new cap and rotor today. Then I'll start pulling plug wires to see if there is any difference. I'll also check the plugs to see what they look like. I just cleaned them before I started running the motor.


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## pappasteve (May 31, 2007)

I bought a cap and rotor and installed them. I checked the plugs and they where black and sooty. I started the car which takes about 3 or 4 tries before it will start. The car ran the same. 

I tried pulling the vacuum line off the intake that goes to the brake booster and the motor runs very smooth. Better than it has since I have had it. The idle had been pretty low before and after pulling the vacuum line off it raised the rpm up to what seemed to be more normal. I'm going to try and pull off the IAA unit. The manual I have says it is suppose to add air into the intake to stabilize the idle 

Any suggestions on how to check this unit.


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## pappasteve (May 31, 2007)

Well I took the IAA unit apart and it was clogged with carbon deposits. I cleaned it and put it back on and the car now idles correctly. The motor still runs rich but is improving. At least it now idles correctly. I'm going to check the throttle position sensor and make sure it is set right.


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## pappasteve (May 31, 2007)

Checked the throttle position switch and it was okay. Did get the motor to rev up better by uping the fuel pressure to around 25 psi. At 25 psi the idle gets worse and more black exhaust comes out of the tail pipe. 

What type of plugs are best to run in this motor? It has a autolite platnum in it now.


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## bikeman (Dec 26, 2006)

I believe the fuel pressure should be 37 on it. Try cleaning the throttle body with some throttle body cleaner in a spray can, use a tooth brush, it must also be pretty dirty. I once had one ignition wire bad, it would start good, idle good but stumble on take off, then OK when cruising on my '87 Nissan. I tried the Bosch platinums but found them not lasting any longer then base NGK or Champions, the intake and exhaust are different numbers, make sure they mark what is what when buying the plugs and double check.


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## pappasteve (May 31, 2007)

I've cleaned the throttle body already. I'm going to look at the computer for diagnostics. Is there more than 1 water temp sensor on the engine. I'm thinking that maybe the sensor is bad causing tha computwer to think the motor is always cold and make it run rich. It seems to run better now at higher rpm's since I turned the fuel pressure up to almost 30. But at idle is misses out due to running to rich.


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## bikeman (Dec 26, 2006)

Only one temp sensor (code no 13). Are all the plugs fouled or just one? Rule out the ignition wires before going any further.


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## pappasteve (May 31, 2007)

All the plugs are fouled. There is 2 temp sensors, one is for the gauge in the dash and the other goes to the computer. They both seem to be working okay. 

Does the nissan stanza manual explain how the run diagnostics with the computer?


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## pappasteve (May 31, 2007)

I tried uplugging the air flow meter and it made no difference at all (thats while the motor was running).


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## bikeman (Dec 26, 2006)

Yes it has quite an extensive "electronic control system inspection" section as well as a "self-diagnosis" area to pull codes. What about the air temp sensor?


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## pappasteve (May 31, 2007)

I haven't found that one yet. I'm going to try and pick up a service manual that has more info in it. Thanks for all the replies.


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## bikeman (Dec 26, 2006)

Sorry, I've been away for a few days, the manual I have was from the dealer.


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## pappasteve (May 31, 2007)

the manual I'm trying to get is a nissan service manual for 87 only. It should have a lot more info the the haynes manual I have now.


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## bikeman (Dec 26, 2006)

exactly what I have, only covers one year and one car only, well worth it.


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## pappasteve (May 31, 2007)

Will I didn't get the manual I was wanting to get. Is the 87 stanza wagon manual basicly the same as 87 stanza car manual? Did they have the CA20E motor also. I looking for info on the fuel delivery and computer diagnostics.


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## bikeman (Dec 26, 2006)

I also have the 87 Stanza Wagon manual, it should cover most of the same. It was the same car in wagon version and also the wagon came with optional 4WD.


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## pappasteve (May 31, 2007)

Thanks bikeman.

I found one today for a 87 stanza car for $15. Should have it in a week or so. Any suggestion on what could be causing the over rich condition. The plugs foul out after about 20 -30 minutes of running. Whats the best way to check for faulty injectors?


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## bikeman (Dec 26, 2006)

Check the PCV valve and that the hose is not collapsed or blocked. While running and hose removed from valve there should be a hissing sound and a strong suction to your finger when plugging it. With the injectors, they either work or they don't, if they are really dirty then they can cause plugs to foul due to a bad spray pattern and incomplete combustion. How old is the oxygen sensor? Is the timing correct? Air filter? According to the manual there is a fail safe mode when the Air Flow Meter is out of spec, the injector pulse duration is fixed at a preset value (at rpm under 2400) or fuel is not injected (when rpm is over 2400). Have you pulled one wire out at a time while running to see if there is much of a drop in idle as a wire is disconnected. If spark is strong there should be quite a difference when a wire is pulled in idle quality, if spark is weak very little or nothing changes. Do you know how old the ignition wires, plugs, rotor and cap are? Use something to grab the wire boot rather then your fingers, you'll get a good zap otherwise!


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## pappasteve (May 31, 2007)

WOW! This manual I just got has everything you could ever need and then some. All I need now is some time to work on it. I'll post what I find out is wrong.


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## bikeman (Dec 26, 2006)

nothing beats a dealer manual specific to a car. good luck, hope it works out.


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## pappasteve (May 31, 2007)

Did some checking with the computer in mode 3. It came up with code 13 which is the water temp system. I tried to do a little checking and it looks like the sensor is okay but the voltage going back to the computer is suppose to be between 5 and 1 volt. I'm only getting .011 volts. Looks like theres a problem with the wiring or connection. I'll try and check the continuity Friday morning.


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## pappasteve (May 31, 2007)

I have checked out the code 13 (water temp sensor) I have a 4.97 volt supply to the water temp sensor (thats with the harness connector disconnected - only 1.8 volts connected). The voltage back to the computer is only .011 volts. It should be somewhere between 5 and 1 volts. The wiring is not open or shorted anywhere. The water temp sensor resistance is within the acceptable range.

Can the computer be tested to see if it is bad? Could a dealer do this?


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## bikeman (Dec 26, 2006)

In that very same section it mentions checking the power source and ground circuit for ECU. It's further in the chapter of my book, have you done this?


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## pappasteve (May 31, 2007)

Yes I checked all the power and ground circuits on the ecu and they were all good. Thats why I'm thinking that the ECU is probably bad. Is there any place to get one tested?


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## bikeman (Dec 26, 2006)

It might not be such a bad idea and take it into Nissan dealer for a diagnostic, at least tell you what is or isn't good at this point. Their scan tools can read live data as car is driven or idling, can tell them how good something is operating.


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## pappasteve (May 31, 2007)

I have something like that for a OBD 2 system. The computer shows a code 13 fault but would scanning only tell you that it is a water temp sensor system fault. Would it actually tell you the computer is bad. While doing the testing on the water temp sensor I tried to disconnect the # 26 wire connector on the ECU (but couldn't unhook it from the connector) so I could plug it back on to the computer, start the car and see if the voltage was correct going back into the computer. 

I know that the voltage coming out of the computer is correct. Voltage going to the sensor is correct also. If I unhook the wire from the connector going back to the computer from the sensor and check the voltage coming out of the sensor the voltage is correct. 

I've done some diagnostic one newer vehicles and understand what you mean as far as getting live data from the computer. I think if I took it too the dealer they would only tell me I have a water temp sensor system problem. I'm not sure they could tell me the computer is bad (if indeed it is bad). You would still have to do the testing like what is in the service manual to see what is wrong with the system. That's what I'm doing now and everything is showing up normal. That's why I think it is the computer. I hate to take it someplace just for them to tell me what I already know.

I'm going to go do some more checking this morning and see what I can come up with.


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## pappasteve (May 31, 2007)

May have accidentally figured out my problem. I went out and rechecked the codes in mode 3 and was still getting code 13 and picked up code 41 (air intake temp sensor). 

I tried just hooking a jumper wire from the body grounds (grounds from the computer) to the negative battery clamp. Started it up and it ran much better and tried checking codes again in mode 3 and got code 44 which means it PASSED! 

I'm going to get some wire and connectors to hook up a extra ground from the body conections to the battery direct. Replace the fouled out spark plugs and put on the air box and hose in front of the Mass air flow. 

Let you know how it works out. Thanks for for all your help and support Bikeman.

Steve


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## pappasteve (May 31, 2007)

well I don't have any more codes according to the computer, but it still runs rich. I checked the computer in mode 1 and 2 with the engine running and it shows that the enigne is in open loop or closed loop and running rich.


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