![]() |
|
Welcome to the Australian Ford Forums forum. You are currently viewing our boards as a guest which gives you limited access to view most discussions and inserts advertising. By joining our free community you will have access to post topics, communicate privately with other members, respond to polls, upload content and access many other special features without post based advertising banners. Registration is simple and absolutely free so please, join our community today! If you have any problems with the registration process or your account login, please contact us. Please Note: All new registrations go through a manual approval queue to keep spammers out. This is checked twice each day so there will be a delay before your registration is activated. |
|
![]() |
|
Thread Tools | Display Modes |
![]() |
#31 | ||
T3 TE50 Blueprint
Join Date: Apr 2005
Posts: 934
|
A couple of things look strange to me. Your tps voltage stays on 1.18v even when you blip the pedal. That’s not what you want to see. Your MAF voltage is approx 0.8v at idle. Is it a stock MAF? Usually a stock engine and MAF are between 0.95v and 1.05v at idle, or thereabouts. This suggests to me that air is getting in elsewhere. Your spark values are chasing up and down trying to stabilise the idle 16-29 deg. If it’s happy it should only fluctuate a degree or two around 18 deg.
|
||
![]() |
![]() ![]() |
![]() |
#32 | ||
Regular Member
Join Date: Jun 2009
Posts: 129
|
Ooh, good point. I’ll do a log of throttle position voltage as I press the pedal down
|
||
![]() |
![]() ![]() |
![]() |
#33 | ||
Regular Member
Join Date: Jun 2009
Posts: 129
|
Yep MAF is standard
|
||
![]() |
![]() ![]() |
![]() |
#34 | ||
Regular Member
Join Date: Jun 2009
Posts: 129
|
TPS seems to be ok, video below shows the voltage sweep seems to be ok from closed to WOT?
|
||
![]() |
![]() ![]() |
![]() |
#35 | ||
Regular Member
Join Date: Jun 2009
Posts: 129
|
The video below shows the MAF swings up to about 3.5v with a full throttle blip, does this sound about right?
Geez it's spins to 5000rpm quick! If I can get this bloody idle hunt issue sorted I'll be a pig in ****! |
||
![]() |
![]() ![]() |
![]() |
#36 | |||
Regular Member
Join Date: Jun 2009
Posts: 129
|
Quote:
|
|||
![]() |
![]() ![]() |
![]() |
#37 | |||
Regular Member
Join Date: Jun 2005
Location: Tweed Heads
Posts: 404
|
Quote:
Basically same setup as this. I disconnected the air pipe after the air cleaner and put a rubber glove with some tape over it to seal the system. Disconnected the vac hose at the brake booster and hooked into that hose(goes to manifold). Worked well.
__________________
2001 AU2 220 XR8 - Build thread |
|||
![]() |
![]() ![]() |
![]() |
#38 | |||
Regular Member
Join Date: Jun 2009
Posts: 129
|
Quote:
Champion thanks Ben! IOU 🍻 |
|||
![]() |
![]() ![]() |
![]() |
#39 | ||
Regular Member
Join Date: Feb 2010
Location: Melb
Posts: 167
|
Can you include MAF airflow (grams/sec) in your log? Should be about 6.5-7 g/s at idle once warmed. If MAF airflow is low at idle and fuel trims high, you might have a big old vacuum leak (unmetered air). Check the PCV valve and the rubber elbow on the fuel pressure regulator, I had a hard-to-find leak at the latter.
|
||
![]() |
![]() ![]() |
This user likes this post: |
![]() |
#40 | |||
Regular Member
Join Date: Jun 2009
Posts: 129
|
Quote:
You make a really good point, as the revs increase during idle hunt the airflow number isn't changing, so the air must be coming from somewhere else? You can see airflow increase when I take it up to 2300rpm, but the idle hunt number doesn't move... |
|||
![]() |
![]() ![]() |
This user likes this post: |
![]() |
#41 | ||
Regular Member
Join Date: Feb 2010
Location: Melb
Posts: 167
|
Thanks, yep looks like a vac leak, that idle MAF airflow is well below the normal range. Unmetered air getting in, so it runs lean and the fuel trims go strongly positive to try and compensate. If you go for a drive and log it you'll likely see it running lean/fuel trims going right up during closed throttle, then come back to normal with more load (more load lessens the effect of the vac leak).
The O2 sensors look to be switching OK to me but it doesn't hurt to replace them anyway at this age. |
||
![]() |
![]() ![]() |
![]() |
#42 | ||
Regular Member
Join Date: Jun 2009
Posts: 129
|
Update -
It seems there’s a leak in the righthand header before the O2 sensor. There’s a definite “ticking” sound coming the exhaust connected to #3 or #4, which becomes harder to hear when the engine is hot. It’s going in to get it sorted on Monday. I’ve a horrible feeling it will be like everything else so far, it needs to be fixed but isn’t the source of the problem |
||
![]() |
![]() ![]() |
![]() |
#45 | ||
Regular Member
Join Date: Jun 2009
Posts: 129
|
That wasn’t it. New gaskets and now no smoke but idle problem is still here.
I think it’s a fuel pump/regulator issue, I’ll start another thread |
||
![]() |
![]() ![]() |
![]() |
#46 | ||
Regular Member
Join Date: Jun 2009
Posts: 129
|
Here’s an interesting observation, the car runs a lot better with the fuel pressure regulator vacuum line disconnected and plugged.
With vacuum to the regulator the short term fuel trims are positive 20/25% at idle and positive 10/15% while driving. With no vacuum to the regulator the fuel trims at idle are around positive 10% and floating around zero while driving. Pressure seems to be okay but I have a new regulator on the way just in case |
||
![]() |
![]() ![]() |
![]() |
#47 | ||
Regular Member
Join Date: Jun 2009
Posts: 129
|
Update: problem solved!
This issue started about a few weeks after I bunged on some Tickford TE50 heads and an intake insulating spacer. I'd already fitted an SS CAI. It was pretty obvious the thing was running lean at idle and as a he thread shows we chased a lot of things to try to find the cause. It had to be a vacuum leak, that is air entering the intake without being registered by the MAF sensor. Then it hit me, what if there's now more air coming through the MAF and the engine tune is now out of whack? I went for a run with the OBD2 connected and Forscan running, I gave it the boot a few times to datalog the MAG flow and MAF voltage. I came home and wrote it out in a table, then compared it to the MAF transfer in the ECU's tune (using a Moates Quarterhorse and Tunerpro... Bugger me it was a reasonable way out. The engine is getting more air than the tune expects. I thought perhaps the ECU would learn from the MAF voltage and adjust itself so the car idled better, but as we know the short term fuel trims chased the lean reading from the O2 sensors all over the place. So I adjusted the time's MAF transfer table to match the MAF data I had logged. Problem solved!!! There's still a bit of tweaking to do but the mad idle hunt has gone. Thanks for your help and advice blokes. What a top lesson this has been! Here's the before and after MAF tables... Before ![]() After ![]() |
||
![]() |
![]() ![]() |
This user likes this post: |
![]() |
#48 | ||
FF.Com.Au Hardcore
Join Date: Nov 2006
Location: Sydney
Posts: 1,334
|
Glad you got that sorted but there's something else I want to direct your attention to. There is an old thread in FFAU about issues with wiring design of some aftermarket O2 Sensors for the AU V8. Some of them incorrectly earth the sensor through particular wires, which forces the voltage of other sensors to be mis-read. NTK sensors correctly earth their O2 sensors for the AU V8 so do not have this problem.
Best you do a search for that thread- it's pure gold. Cheers |
||
![]() |
![]() ![]() |
This user likes this post: |
![]() |
#49 | ||
Starter Motor
Join Date: Apr 2022
Posts: 3
|
Did you get to the bottom of the surging idle
|
||
![]() |
![]() ![]() |
![]() |
#50 | ||
Fordluva
Join Date: Dec 2010
Posts: 105
|
Did you check the o2 fuse in the engine bay fuse box
Also check fuel pressure is within specs (can get to high) |
||
![]() |
![]() ![]() |
![]() |
#51 | ||
Regular Member
Join Date: Jun 2009
Posts: 129
|
Sorry for the late reply Regan. I got it to idle steady by tweaking the MAF transfer table.
Then I had another issue with “bucking” at light throttle levels while cruising below 2000rpm. Above 2000 it was ok, but below 2000 it was like I was towing a trailer that was jerking on the back of the car. I thought of blocked injectors, valve issues with the Tickford heads I’d fitted. It drove me nuts. Just found the issue thanks to some ideas on OS forums - the Tickford heads have 1.72 rockers so it’s effectively got more cam duration. At light throttle there’s more vacuum and with increased valve over lap (due to the bigger valves and increased duration) exhaust gas is being drawn back into the cylinder and intake plenum. The solution seems to be to reduce the light throttle spark advance in the “PT Spark Adder for ECT vs Load” table. I’ve got the advance cut by 15 degrees at 5% load. Now it’s cruising nice and smooth |
||
![]() |
![]() ![]() |
![]() |
#52 | ||
Next upgraded Mk1 Leopard
![]() Join Date: Jan 2005
Location: Sydney, in the burbs
Posts: 4,909
|
good to hear
__________________
Plastic Surgery 1 AUII Monsoon Blue How 2's: Change rear view mirror, Install backfire valve, Change foam front seats, Install auto transmission cooler, Replace Trans Shift Globe, Remove front door Trim, Paint AU headlights, install door spears, Premium Rear Parcel Shelf, go here...
|
||
![]() |
![]() ![]() |