SayDfuse

Hello, first i would like to say that i've been lurking and learning about the RX-8 for a long time on this website, i never needed to make an account since most issues that have came up were fixed with a quick search but now i've hit a brick wall.

BACK STORY: A few weeks back me and my dad bought a 2004 Rx8, 4 speed auto, 127k miles, the engine was overheated and burned out by the previous owner. from the looks of it, the car hadn't been started for a long while when we got it. The engine would spin but wouldnt turn on.

WHAT WE TRIED: We bought a new engine that came out of a running car with 50k miles. it was from a 2004 manual 5 speed. we swapped the old engine with the new one, but kept the old wiring, old computer, and old transmission. as well as everything else not pertaining to the main engine. it also has the updated N3Z2 starter from the old engine.

We changed the oil, tranny oil, added gas (since the old one was probably no good), new oil filter, reset ESS (aka 20 brake pumps) , checked and cleaned the ESS sensor, Checked and cleaned MAF sensor and made sure to keep the battery charged at all times. We also checked the spark plugs, coils, and wires in the new engine and they looked clean. we bought a new radiator but haven't yet installed it.

CURRENTLY: Today we went and cleaned up the engine and tried to crank it. The first couple of times we tried it just spun over and over. Eventually after a while of trying we got it to crank (had to give it gas while cranking). At first it would only stay on if i was giving it gas, a lot of white smoke came out and i let go of the gas after about a minute and it stayed on like that (everything sounded normal) for about 5 minutes, after that i tried to rev it up to 2,500 but my foot slipped slightly and the revs dropped and caused the engine to die (this is where i'm stuck) engine temperature was at about half way in the gauge.

We tried turning it back on a bit later but it went back to just spinning over. after fiddlying around with the car we noticed a cable was unplugged at the transmission (we have no idea where it goes, ill try to get a picture soon so you can help) my dad said it shouldnt have anything to do with the engine so we tried turning it on again and it finally did (took about 10 seconds of cranking while giving it gas, as well as a battery charger connected to the battery and some starter fluid) some more white smoke came out but a lot less than the first time. I kept my foot on the gas and kept RPMs at about 2,000. after about 2 minutes i tried slowly revving it up to 2,500 and kept it there for about 30 seconds then suddenly the engine died. (this is also where i need help, i have no idea whats made this happen) the engine fans came on shortly after it died.

CODES: the codes the car gave us were;
Engine: P0301; Cylinder one misfire detected. (we put different spark plug and wires on rotor 1, then erased the codes but they still came back when we started it the second time)
Transmission: U0101; Lost communication with TCM.

I'd appreciate any help at all. if you need any information just ask and ill try to answer. THANK YOU!!!!!

dannobre

iTrader: (3)

You need to hook up the TCM wiring to the transmission

It likely will need new plugs....which coils did you use..ones on your original engine...or off the new one?

SayDfuse

The first time we cranked it it was using the wires and the plugs from the original engine. The second time it was using the plugs and wires from the new engine we bought. and We have no idea where to hook up the transmission cable, i've searched but cant find any DIY or pictures of it.

we also used the coils from the new engine. we didnt take them out but we assumed whatever condition they are in is better than the old engines.

patriotjj

Even with the items being from the new engine, 50k miles is well over the time for needing to replace the plugs/wires/coils ?

dannobre

iTrader: (3)

There should be several plugs on the side of the tranny..there might be an isolator cover over where they are pluggged in

Did you use the engine harness from the AT engine??

SayDfuse

yes, all of the transmission wiring we used was from the automatic, do you have a picture of it by any chance?

SayDfuse

The engine came out of a running car so i assume they are in a decent working condition at worst, and at best they were recently changed. They were very clean and had a "new" look to them when we took them out.

dannobre

iTrader: (3)

Did you use the engine harness from the MT or from the AT??

SayDfuse

Sorry, i misunderstood your last post. Yes we used the engine harness from the AT transmission.

dannobre

iTrader: (3)

I would start with finding the electrical plugs location and plug it in....after that...go over the wiring harness and make sure everything is plugged in correctly elsewhere

There are so many variables that you will need to confirm everything is OK before we can be much help

SayDfuse

Thank you, we will find the plug and plug the cable, as well as check EVERY connection in the engine and transmission. That should take care of the transmission code i asssume.

any ideas on what can fix the misfire issue? or what things we can check first to start narrowing down the source of the problem?

dannobre

iTrader: (3)

After you check the wiring then see what happens....

Ignition is known trouble spot... coils are basically disposable

SayDfuse

how can i know for sure if the coils are bad? if they have a slight white spot, does that mean they're bad? same with the spark plugs and wires?

patriotjj

50k miles is ALOT of miles if its not BHR

Loki

iTrader: (1)

The white spot doesn't mean anything. There is a somewhat reliable test with a multimeter, the procedure is posted somewhere in the tech section, but even that is not 100%. But yes, 50k is beyond their useful life.

I would suggest checking a few common engine swap mistakes first: that the coils are plugged to the correct harness plugs, and that they plug wires are connected to the correct spark plugs. Likewise, that the injectors are plugged in in the correct order. It's very easy to mix those up.

SayDfuse

can you explain what order the coils are supposed to be in? i know the wires have to plug up to T1, T2, and L1, L2 respectively. ill make sure to double check those tomorrow. i also dont really know what order the injectors are supposed to be in. i havent checked, the injectors came pre-installed in the engine. i did find this however, but dont know how to interpret it https://www.rx8club.com/series-i-tec...r-info-150432/

are the injectors color coded?

Loki

iTrader: (1)

Negative on plug order, see here: https://www.rx8club.com/rx-8-discuss...ileage-243805/

For injectors, I don't have a handy graphic, but I meant the wire connections, not the actual installation in the engine.

But having the plug wires wrong will certainly do that.

SayDfuse

Quick question, the trailing and leading OEM spark plugs are different. the manual says to install the correct ones on their respective place (leading or trailing). but the ones that came with the new engine seem to be all the same. would this have any effect on the engine? they also dont have the flat head. they look like any other cars apark plugs. thank you by the way.


This is the flat OEM spark plugs.


This looks like the ones my new engine came with. the difference is pretty big in the head of the spark plug vs flat.

Loki

iTrader: (1)

Dear god. And you say this thing ran?
So yeah, you're going to want to use proper rotary spark plugs, in their respective places.

Let's just take this one step at a time. We can help, but I have the feeling it's going to take a few iterations.

SayDfuse

Oh man... I had no idea. Could this have caused any damage to the rotors? We put in the flat spark plugs from the old engine at first but they really look dead so we tried the ones from the new engine in the rotor that had the misfire , and yes it ran but now I'm worried it might've damaged something.

Loki

iTrader: (1)

Let's hope not. The risk is the spark plug protrudes into the combustion chamber and the apex hits it as it passes over. I don't know of any actual cases of this though... it's not a common issue :S

When you say the new engine is out of a 5-speed manual, is it still a 4-port engine? Also known as the 192 engine in the UK. Where are you located?

SayDfuse

Alright, I really really appreciate the help. Tomorrow we'll clean the old flat spark plugs and put them in the correct place as well as check all the wiring and the injectors wiring and see what happens. I'll make sure to update tomorrow with the results

By the way, could the cat be damaged or clogged from the last guy who burned out his engine? If so, how should I clean it? Removing it should be easy

Loki

iTrader: (1)

Yes it's possible the cat is bad, but this wouldn't show up in a start-up situation. At full throttle - yes, but I would say let's get her to idle first.
You can't really clean it, it will need to be replaced or gutted (which won't pass emissions depending on where you are located).

Also what do you mean by "burned out"?

Mysterion

Here is what you should have for spark plugs:
2 x NGK RE7C-L / 6700 / Leading
2 x NGK RE9B-L / 6701 / Trailing

Attached picture shows what they look like:

patriotjj

IMO you should just go snag the right plugs at a locAl autoshop for 20 bucks a pop just to be on the safe side