Jump to content
View in the app

A better way to browse. Learn more.

300ZX Owners Club

A full-screen app on your home screen with push notifications, badges and more.

To install this app on iOS and iPadOS
  1. Tap the Share icon in Safari
  2. Scroll the menu and tap Add to Home Screen.
  3. Tap Add in the top-right corner.
To install this app on Android
  1. Tap the 3-dot menu (⋮) in the top-right corner of the browser.
  2. Tap Add to Home screen or Install app.
  3. Confirm by tapping Install.

Idle issues

Hi guys

 

I'm a noob on here having recently become the owner of a 1994 UK spec TT Manual.

 

To be fair the car was in a bit of a state when I got hold of it but the plan is to slowly bring it back to life.

 

It had started to be stripped for parts so I've reinstalled the interior and done the usual maintenance like sparks, cleaning all the connectors, new fuel filter and checked ECU for codes but getting the 55 code so all good.

 

When I start it up if will fire but idle really rough before cutting out. I've checked for boost leaks etc and nothing. I tried disconnecting the MAF and car idled perfectly but wouldn't rev past 3k. Fitted a new MAF but the problem is still there when I connect it up.

 

It does have a set of aftermarket BOV's on it and I read that these can cause problems in a MAF setup by causing over fuelling and flooding the engine?

 

Just wondering if anyone had any thoughts?

 

Cheers

 

Stuart

Featured Replies

Welcome to the forum Stuart!

 

First things first, remove the BOVs. They're pointless and do absolutely nothing for the car's performance and can cause rough idling. I don't think this is your problem though. Try thoroughly cleaning ALL the contacts (focus on the MAF, coilpack, injector and PTU connectors). Check the hoses for any splits, then, if you have ConZult, check the TPS setting. You can check this with a voltmeter (I forget the voltage) and adjust. Also clean the connector up to that. When these are not set correctly, they can cause rough idling and cause the car to cut out.

Edited by Funkysi

Just checked - TPS voltage needs to around 0.45v closed throttle. If it doesn't adjust, it's likely to be faulty or one of the wires/contacts are bad.

  • Author

Cheers Funkysi. I've already cleaned the MAF, injector, coil pack, PTU, CAS and detonation connectors with electrical contact cleaner and there's no corrosion whatsoever on any of them

 

 

Sent from my iPhone using Tapatalk

It is grey and was on eBay but my two eldest persuaded the wife to let me keep it :)

 

 

Sent from my iPhone using Tapatalk

 

Good choice! Looked like it did need a bit doing to it but will be well worth it.

I've also cleaned the TPS connector too

 

 

Sent from my iPhone using Tapatalk

 

Spend some time on the TPS. I've added the voltage figure above. :)

  • Author

Well I've fitted new windows as three of them were missing and reinstalled all the seals etc so it's water tight again :) it was also suffering from the dreaded soggy spoiler so that's come off and going to keep the smooth rear look

 

 

Sent from my iPhone using Tapatalk

 

1) checked ECU for codes but getting the 55 code so all good.

 

2) When I start it up if will fire but idle really rough before cutting out.

 

3) I've checked for boost leaks etc and nothing.

 

4) I tried disconnecting the MAF and car idled perfectly but wouldn't rev past 3k.

 

5) Fitted a new MAF but the problem is still there when I connect it up.

 

6)It does have a set of aftermarket BOV's on it and I read that these can cause problems in a MAF setup by causing over fuelling and flooding the engine?

 

 

Ok have picked the bones from your original questions which should help a bit as some more information from youirself will help with any advise:

 

 

1) Be aware getting code 55 is no indication that all is well, in fact it covers very little of the engine as the system is only OBC1 which unlike later modern systems does not self report, in the main only giving an error code if one of the few sensors are disconnected or short circuited, the issue with this is something such as the afm or o2 sensors can give very poor and incorrect readings but as a signal or reading is been received be it incorrect the ecu will not see it as a fault.

 

2) Starting up is a good thing of course, the cutting out does it die slowly finally giving up or a sudden stop?

 

3) How did you check for boost leaks?

 

4) A disconnected maf will produce be one of the few fault reactions and code from the ecu, it also restricts the revs as a sort of limp home mode, as it runs better with it disconnected it points to a fault maf or air/boost leaks.

 

5) A "new" maf, as they are around £400 I am guessing you mean either a used one or a new one of the £80 units off e-bay? the later are rubbish and do not work correctly anyhow, if a second hand one unless you have seen it proven on another zed it could also be faulty.

 

6)Bovs are pointless on road cars unless you just like the sound of them, unfortunately they also can cause air leaks and be slow to close at high speed again causing problems with the fuel / air mix. However unless they are wide open I doubt they are this problem you have at the moment.

 

Given at least 50% of the zeds I have dealt with over the years come to us with air/boost leaks some been more serious than others, at best it increases boost build up time (lag) and at worse makes the car flat and down on power, fuel use is worse and not good in the long term for such things as the spark plugs, often plugs have to be changed after been run in a poor performing engine.

 

So a bit more info please to the above to aid the diagnosis

Jeff TT

Edited by JeffTT

  • Author

Cheers for the reply Jeff. The car fires and will idle at around 2k revs before slowly spluttering out. It was a cheap £80 eBay until but if they are unreliable maybe my existing MAF is ok, unfortunately I don't have another Z around here that I know about to test it on.

 

 

As for the boost leak test I borrowed a smoke machine from work and tried that with but I suppose that doesn't mean that there isn't any.

 

 

Sent from my iPhone using Tapatalk

I'll have my zed back in a few weeks, could test it on that if you havnt found the problem by then.

Cheers Mogsy... Where bouts are you?

 

 

Sent from my iPhone using Tapatalk

 

I'm in Tranmere so not far away from Neston.

Ah brilliant! Didn't realise there was a few zeds round here!

 

 

Sent from my iPhone using Tapatalk

 

Yeah & a few in chester & north wales too.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Unfortunately, your content contains terms that we do not allow. Please edit your content to remove the highlighted words below.
Reply to this topic...

Recently Browsing 0

  • No registered users viewing this page.

Important Information

Terms of Use

Account

Navigation

Search

Configure browser push notifications

Chrome (Android)
  1. Tap the lock icon next to the address bar.
  2. Tap Permissions → Notifications.
  3. Adjust your preference.
Chrome (Desktop)
  1. Click the padlock icon in the address bar.
  2. Select Site settings.
  3. Find Notifications and adjust your preference.