1991 300ZX non turbo diagnostic device

[300ZXing]

Hello everyone!
Just looking for good recommendation for OBD 1 or 2 diag tool . Which one to buy and best prices maybe?
Having problems with intermittent rough running at 2000 to 2800 rpm. This usually happens after 5 minutes of driving at 65 mph for 5 or 6 miles then stopping at light. After the red light traffic stop it runs terrible. I just putter it in a few more blocks to work. When I come back out to go home it's running great again on the highway but the traffic light I have to slow down for will kick in this puttering .... new plugs, new maf x 3, new tps x 3 , and much more with no results. This is going to the end of a two year tinkering project. Love working on this z car though. Any suggestions?

[Ace2cool]

Well the best monitoring system is probably Nistune, but sounds like you just want to pull codes, which you can do from the ECU.

http://www.nicoclub.com/archives/nissan ... ostic.html

The car is OBDI, so no need for OBDII reader.

[ThisIsSparTTa]

You can get a USB Consult Cable to hook up to your computer from the various Z shops, or from Ebay. The Consult connector is on the drivers side. As far as software goes, you have a few choices, and I don't have an opinion, because I haven't bought yet, just used someone elses. I've heard ConZult is legit, but is pricey. There's a few others floating out there as well. The software should give you the ability to pull codes, monitor sensors, do power balance tests, etc.

[300ZXing]

Thank you.
Just checked white wire tps to adjust to .45 and discovered that the engine idle increased the second I touch the postive probe of my voltage meter to white wire. Also the motor will run better if I ground the black wire on the tps.
Weird but probably should replace tps. This makes 4 tps's in one year. Gotta 2000 rpm problem intermittent.
I will look for the Nistune and ConZult.

[Ace2cool]

Yeah, sounds like a TPS issue for sure.

[300ZXing]

Replaced tps complete with connectors new down to wiring harness. Runs rough still at idle but goes away after 10 minutes of traffic. Was running smooth first 10 minutes in the morning. Nissan tech recommended hard to find missing is probably weak coils responding to engine temperature. Ordered couple of coils to move around to different cylinders. The driver's side left bank of cylinders has the missing history. Got one good smooth run down the road for about 5mins after swapping coils around on left bank but still intermittent.

[300ZXing]

Thanks, Ace2cool for responding.

[Ace2cool]

Is it an intermittent miss or is it a pretty solid persistent one till it warms up?

If it's a solid one, then try the power balance test. Pull coil connectors one at a time and see if it changes.

[t.mcginley.jr]

Did you actually pull the codes yet at the ecu?

[300ZXing]

I stopped switching the coils around after adding 2 more. The intermittent missing at idle is now happening at the same time egr whines. Back driver's side of motor making this vibration growl at egr area for maybe 20 seconds or more. When the noise stops the motor runs smoothly again. It became more pronounced after replacing the coils on driver's side of motor. The other 3 cylinders on passenger side have been great. Tested each cylinder by pulling coil plug with engine idling. Hope it's not the EGR valve, I've heard the whole motor has to be pulled to get to it. Any suggestions?

[300ZXing]

no codes yet waiting on my obd1 ordered at ebay

[t.mcginley.jr]

There's a way to do an egr bypass without removing the valve itself.

http://z32.wikispaces.com/EGR+Removal#P ... %20Removal

As for pulling codes, why not just do it now? you only need a flathead screwdriver

[Ace2cool]

http://www.nicoclub.com/archives/nissan ... ostic.html

Click this link, and do what it says. Return the OBD reader. It doesn't do anything you can't do here for free.

[300ZXing]

Thank you, thank you.
I have learned some much in the past 2 hours about Curing Erractic Idle (part 1 and part 2). ECU code came up great 33, and 53 that show (exhaust gas sensor circuit Left 33) , (exhaust gas sensor circuit Right).
Do these sensors thread into exhaust just behind manifold?

[t.mcginley.jr]

Do these sensors thread into exhaust just behind manifold?

Yes. The "exhaust gas sensors" are the oxygen (O2) sensors that are threaded into the exhaust manifolds. Since both are showing up faulty, you probably need new ones. When they go bad, they respond slower than they should and also send the wrong signal to the ECU, so it thinks its either running too lean or too rich and messes up the air/fuel ratio. This causes all kinds of weird problems, especially with idle. You can get new OEM O2 sensors, but I'm running a pair of Bosch ones without any issues. They were around $50 each on RockAuto.com

[300ZXing]

I also used the ECU mode II test to get codes for the flashing check engine light but never got the blinking for left or right side. Ordered sensors for both sides. Hope these parts put an end to this mystery. Oh, by the way, you guys (monitors) really know your stuff. Thanks for the reference threads. What a good way to "Give Back" to all us little guys just tinkering around in our garage.

[Ace2cool]

Hey, most of us are the same. We've just been doing this since we got our cars, lol. And don't give just the moderators credit. Most of the best helpful tech comes from the other members. I'll default to Ziggy or t.mcginley if there's a confliction of answers. They usually know it better than me, lol.

All for the love of Z's!

[t.mcginley.jr]

I also used the ECU mode II test to get codes for the flashing check engine light but never got the blinking for left or right side. Ordered sensors for both sides. Hope these parts put an end to this mystery. Oh, by the way, you guys (monitors) really know your stuff. Thanks for the reference threads. What a good way to "Give Back" to all us little guys just tinkering around in our garage.

Your welcome! We all started out "just tinkering" at some point. Hell, I've only owned my Z for about 9 months now but I've spent hours and hours doing research on the million questions I had. The great thing about these cars is that if you have a problem, someone else has likely had the same problem and there's a solution for it. Good luck!

I'll default to Ziggy or t.mcginley if there's a confliction of answers

I try!

[300ZXing]

I am throwing a party in my garage !
O2 SENSORS worked. For the first time in over 2 years my Z runs and idles normal again. The instruction on codes was the key . gotta 33 and a 53 , changed O2 sensors and all is well.

[t.mcginley.jr]

I am throwing a party in my garage !
O2 SENSORS worked. For the first time in over 2 years my Z runs and idles normal again. The instruction on codes was the key . gotta 33 and a 53 , changed O2 sensors and all is well.

Awesome!! I will be doing the same job in about a week. While I THOUGHT that I was running 2 Bosch sensors, at some point I must have had a retard moment and bought two cheap O2 sensors (no idea what I was thinking) Now that they are about 3 months old, I'm already getting codes 33 and 53 Just bought 2 new Bosch 13091 sensors earlier this morning

[300ZXing]

Just a guess but my Z was running really rich like too much gas to air ratio because of sensors. The sensors were running so rich that the black carbon build up doubled. When I pulled them out they were covered with a thick layer of black powder. Probably could have just cleaned them but might as well replace. Now all the little tuning issues are working fine. Just used the cheapest o2 sensors available on ebay. Air flow regulator is probably stopped up too because the only rough running I get now is in the morning on cold start ups. Does anyone know if the lube and oil places advocating running cleaner through plenum ports while revving engine actually works to clean out the exhaust system? Will this re-clog new o2 sensors?

[Ace2cool]

Talking about running seafoam? It doesn't do anything for exhaust.

You can try cleaning the MAF, but usually it won't do much for these cars. If you think it's bad, you should just get a new N62 MAF. However, if it isn't throwing a code, there's probably another problem. There are troubleshooting tips in the FSM to help isolate possible problems.

We host the FSM at http://www.nicoclub.com/FSM

[t.mcginley.jr]

The IACV isn't too difficult to remove really, but you can try pulling hoses off and spraying TB cleaner in while the car is off, letting it dry some, ad then start it up. It probably won't clean it out as well as taking it off but it might help. This article says once it's clean, you can keep it cleaning by spraying some WD-40 in the right places:

http://s95014253.onlinehome.us/63104/157335.html

FWIW I bought some cheap O2 sensors too (APWI brand?) and they're only 3 months old and are already throwing code 33 and 53.