# Code 21 Nightmare!!! Opinions appreciated!



## monstermash (Mar 13, 2018)

Howdy Everyone,

Non-Nissan owner here (I do dream of old Datsuns though  working on a rig and so far it's completely left me in the dark. Vehicle is a 94 Altima GLE. Was pushed into the shop from gas station next door and as the rookie I was given the job of diagnosing it. Learned all about reading the codes on the ECU this morning after my search for an OBDI port failed. 

Vehicle was tossing a code 21, but I'm still getting spark at the plugs. Cranks over just fine although she won't catch and start up. Checked fuel, she's pushing plenty. (I did not check pressure, just confirmed that the pump was working by pulling the rubber line to the fuel rail) The spark plugs were shit so I replaced those and it *seemed* like it almost wanted to catch, but didn't. 

I noticed oil underneath the distributor, but when I removed the cap and rotor it didn't seem like there was much/any at all inside the actual unit. Boss told me to gave it a shot of brake cleaner and blow it out. (Reading more later on, I now know I should have used electrical cleaner and no air at all) After cleaning and giving the points and rotor a quick touch with a scotch brite the car still wouldn't start for me. 

So then I systematically started going through and testing the ignition components. Coil checked out okay, 1 on primary and 12.5K on secondary (10K is the spec, figured it wasn't that far off) Then I pulled the distributor again and performed the CAS test, it was between 1 and 5 volts on wires 1 and 2 as I rotated the shaft. Lastly I tested the TSC? (it's been a long day, what Nissan calls an ignitor) against the table provided by the data system I was using (all data) and it checked out. 

Lastly I pulled the airbox housing and checked for continuity in the resistor/condensor circuit following the FSM for a 1993 I found on this forum, and everything checked out okay. With further reading I thought maybe I could try unplugging the MAF to start in limp mode, but even that wouldn't get me running. 

It looks like all three ignition components, dist, coil, and the ignitor on top of the airbox are all aftermarket parts. 

At this point, and everything I've learned from today, I want to say that it's the distributor. Even though the CAS sensor is working fine, and I'm getting decent spark - I think from becoming oil logged the optical sensor in the dist is toast. I'm guessing no one has changed the PCV valve (reading as how it's such a bitch) and the engine pressure has been building/eventually roasted the distributor. Boss wants me to check timing tomorrow, but from what I've read that's near impossible right? It's on a chain and is quite difficult/rare to skip yes? I don't want to pull the valve cover and re-seal if I don't have to ya know? 

Anyway I'm probably going to order parts for everything tomorrow - Distributor, new coil, and a new ignitor. I figure putting in the distributor first, then the ignitor if that doesn't work, and lastly the coil - but I think the coil is fine. I'm fairly certain that a new distributor will get this car up and running again, but as just beginning my travels on the path to becoming an expert I'd really appreciate second opinions from people who are a lot more familiar with these vehicles. 

Thanks to everyone that takes the time to read this and reply, I truly appreciate it. If I'm breaking any forum rules please just delete this post mods! I promise, I used the heck out of the search function today and read A TON of previous threads. Cheers mates!


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## Car guy (Mar 31, 2016)

Where was the oil "underneath" the dizzy?

Where it mates with the engine or where the cap sits (or both)?

If the latter, then engine oil likely has worked past the dizzy coupling and shaft (inside the engine) and on past the bearing (shaft's bearing) and its seal, into the electrical chamber. Nissan had multiple optical sensors. Some had 2 LED/photo diode pairings and some had 3 pairings. Oil in any of those affects start. Also, oil in the optical module (transistorized circuit) or its connectors could affect start. Normally, the V swing is 0 to 5 and 5 to 0, for the 1' and 180' signals.

Is there battery V at the dizzy? What is that V?

Ground at dizzy good?

ECU and Ign relays turning on (clicking).

Do you have a digital inductive tach (RPM) clamp you can place around SP wire #1 (when trying to start)?

Boss's timing check recommendation is sound, if dizzy is mis-oriented. Timing light should isolate it - once the car fires.

Like the PCV valve thought train.

Worth checking the CTS resistance too.


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## smj999smj (Jan 1, 2006)

If you are getting good spark to the plugs, why are you wasting time on checking ignition components based on a stored code that you don't know how old it is, nevermind spending money on ignition parts? Remember this: always stick to the basics, first, and don't assume! Confirm good spark to the spark plugs from the ignition wires. Confirm that the spark plugs are good. Confirm proper fuel pressure with a fuel pressure gauge, typically around 44 psi static and 34-36 psi regulated. Unless the air filter is clogged solid or there is a giant nest in the air box, one can usually assume that there is not a blockage of air into the engine, but it's simple enough to check. Use a noid light for Bosch-style fuel injectors to confirm the fuel injectors are "firing." If the noid light flashes while cranking, you're good. If not, there's either no power to the injector(s) or the ECM is not pulsing the ground circuit for the injector(s) to operate it/them. Check compression and make sure it's within manufacturer specs. Low compression can be caused by a mechanical issue, such as a chain breaking or jumping (lower chain guides are prone to breaking on these engines), or it can also be caused by poor compression due to the cylinders being flooded, which washes down the cylinder walls. I wet compression test (one where a tea spoon or two of oil is poured into the cylinder before the compression test) can be done to help determine if it's a mechanical issue or flooding issue. 
As far as the OBD I port, it uses the grey, Nissan CONSULT style connector, located by the fuse box under the driver's side of the dash. Unfortunately, OBD II didn't come until 1996.


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