Hi Chaps, this is my first post so I do apologise if it's in the wrong place. This might be a bit lengthy but can be sumarised as follows: 1) Is there a chance my ECU is screwed? 2) Regardless of the answer, does anybody have one for sale for a manual TT that has been socketed?

 

I've been having some intermittent rough running issues, hunting idle for 5 seconds on cold start, misfire on idle, intermittent safety boost. Whilst on a visit to Jimmer at powerzed, he asked me about injectors. It turns out that the ones in the car are not really 555's but a cheap chinese set and he suggested/insisted I change them. Off to pro-tuner I go to buy the new injectors. Whilst there, Greg put a couple of different chips in the ECU to see if the car would run OK until I had the injectors fitted. The car poured with black smoke and ran like a dog. When we put the key in the ignition, for the first time since I have owned the car the check engine light illuminated. Then, when I started the engine the cooling fan came on full blast. Whilst looking at the ecu, the socket has been awfully soldered in, and there is a jumper wire connecting two bits of the board near the socket. Looks like somebody had fried a track or a pad.. Since putting the old chip back in, everything is normal - that is the car still runs like a dog. I can't get the check engine light on the dash, and when I try to check codes either at the ECU or at the diagnostics plug, absolutely nothing happens. I'm booked in to have injectors fitted and a re-map and would like to not waste any more of this poor mans time. Do you guys think this is a chip/eprom problem, or an ECU problem?

 

Otherwise, I have done/had done the following: TPS and hard idle switch calibrated, new ECU temperature sensor, 2 x new oxygen sensors, MAF sensor cleaned and then checked against a brand new one. New plugs, oil, filter. Knock sensor resistance OK, all visible connectors cleaned, tightened and added dielectric grease.

 

ANY help or further suggestions are HIGHLY appreciated. I'd like to replace the ECU anyway, so if any of you guys have a known working one gathering dust, let me know! Cheers!

Welcome to the club Revilo and hope you get your Z sorted.

I’ve got a socketed ecu for sale mate.

Thanks Nick, thanks for your response. A few questions of course: It's a Manual TT ECU? Has the socket been soldered in well? (I'm ashamed to need to ask about this one) - can I just swap my chip into the new ECU and run as normal? (there's nothing of importance stored on the board itself, just the chip?) Finally, how much are you asking? I'll PM from here. Thanks!

Yep, it’s a manual TT which already has a 555cc chip in it (for Deatschwerk 555cc injectors)

 

You won’t be able to PM until your a subbed member I’m afriad buddy.

You do need a different ECU and it seems you have been offered one.

 

Many years ago, i was given a handful of 'copied' chips, tried them, most were duff and caused issues like you explain, fan going bonkers, check light on, roughness, etc, but one i popped in actually worked very well.

 

So based on my experience you're certainly now seem to be barking up the right tree.

Hello and welcome - and good luck in getting your Zed fixed...:clover:

That's very reassuring to hear, thanks!

 

I'm getting to the point where I'm just throwing parts and money at it so fingers crossed with the new ECU. Out of interest, in your case was it the ECU or the chip (or a combination of both)?

 

The current issue is intermittent safety boost (9psi though, isn't safety boost usually 7psi?). Re-starting the car fixes this for a couple of pulls.

 

The current chip I have in runs the car OK but the car itself is not without issues (the IACV had been blanked off so that's something I need to get reinstated..). There's no neutral switch at the moment because I had a new OEM 98 spec gearbox fitted a couple of months ago - and the old neutral switch was wired with a piece of telephone/modem wire.... (!) (timing is set to 15bdc) Because of things like this it's hard to know where these problems start and end for someone like me - just learning the ropes of these cars.

 

My suspisions with the ECU started when Greg/protuner put another chip in. I had always assumed the check engine light bulb was blown, but with the new chip it was illuminated with the ignition on. I have also never been able to check the codes by way of shorting the pins on the OBD plug, or putting the ECU in test mode with the screw/potentiometer on the side of it. Can't even get code 55.. just... nothing! :( No idea if this could be a symptom of either a dodgy chip ( as you had a few), or a cold/dodgy solder joint on the ECU that coincidentally made circuit with all of the messing around in there swapping chips. Anyway, kind of thinking out loud here but we'll see if a new ECU changes the game. Failing that another trip to Jim at powerzed. Trying not to hassle him too much otherwise I'll be on his 'block call' list.. :whistling:

Just to clarify a couple of points for you even though you seem to have a handle on it now.

 

The engine management light on the 300zx is very, very limited in what it tells you, remember this is an old 8 bit ecu chipset and OBD1 NON CANBUS diagnostic system ( thankfully ) the only circumstances that can bring the engine light on with the engine running is 1) a corrupt chip 2) bad solder connection to the chip carrier. ( often followed by the electric ac fan running )

 

The light should come on with ignition but engine not start, goes out as engine is started, anything else is one of the above issues, setting the timing to 15 deg with neutral switch not connected will give incorrect timing, as a very rough rule if the thumb, the cas unit should be central, that is if the belt is correctly fitted ( you will be suprised how many are not ) and it is not stretched.

 

The 300zx has some very odd set up rules, with respect to where you have been it sounds like he is not completely up to speed on the zx engine and as you said Jim is the next person to get it looked at by.

 

Jeff

Out of interest, in your case was it the ECU or the chip (or a combination of both)?

 

I upgraded the engine to 600cc, so some of the unknown origin chips i tried would not of been suitable, always the chip with me, my socketed ECU has always been spot on.

Thanks so much Jeff (and everybody else).

 

Actually I'm only concerned that the engine management light doesn't come on with ignition/engine off at all. With regard to timing, surely with the neutral switch completely disconnected, the ECU will think it's in gear all the time (and therefore timing whilst in gear should be OK, but the idle would be poor)? Just trying to eliminate any other cause for safety boost/pinging issues. The car has been timed to 15 degrees with the neutral switch disconnected. I will hook up the neutral switch this weekend - can I just check this is the procedure:

 

1) Tee-in a wire to pin 44 and run the other end of the wire to the neutral switch

2) ground the other wire coming from the switch

3) warm the car up very well and check the timing in NEUTRAL to be 15 degrees btc at idle (or is the timing advanced in neutral, and 15 degrees is the measurement in gear at idle?

4) would you normally check the timing in gear too?

 

Would you recommend hooking the timing light up to the loop on the wire, or the wire for coil 1 with absoultely no room to fit it under? (there's also another green connector on my timing light, I'll just leave this disconnected I guess)

 

Finally, is there a procedure to check the timing belt hasn't skipped a tooth without having to remove EvERything to get the cover off? I was thinking along the lines of checking the ignition timing for both banks of cylinders. Is there a way to check this? I know you mentioned the CAS adjustment should be relatively centered and I shall check this too ( I understand that this is a rough estimate). Recent compression test showed even readings across all cylinders.

 

Cheers again,

Ollie