doz

doz

Active Member
I'm really struggling now guys. Car runs bad and is well down on power. I'm getting a very low stalled o2 reading from the nearside bank. So far I've changed the Lambdas,cat and full exhaust. I've changed plugs etc and have a mighty good spark. I've checked the injectors and can't see any difference in spray pattern. All 8 work fine. I get a P1300 error code relating to cat damaging misfire on the nearside bank but it's not electrical or fuel. Compression is OK across all 8 pots. If I drive the car at WOT the offside o2 sensor goes high and stays high while the nearside still remains low. I'm guessing I've got an air leak but the only gasket I've yet to check is the lower manifold to heads. I can only think I've done something wrong when I rebuilt it after having the heads recon'd but can't see what I've done. I've checked all wiring to the o2 sensor and if I introduce a rich mixture in to the manifold at idle I can get the nearside o2 sensor to register it but once the mixture is spent it just stalls at near on zero volts. So what could I of ballsed up on lower manifold? I tightened it down evenly and checked rave for correct values. It seems strange I have a air leak yet the water ways at either end are fine do you think the manifold might be warped? I'll strip it off tomorrow but if I don't see anything obvious I'm loath to bolt it back up again. Turning into a proper tit of a job.
 
is fuel pump/filter good & delivering right pressure?also check tank venting which can cause issues,try changing lambdas round you could have a faulty one even if new
 
Let me put this in your ears.... I spent weeks trying to solve a similar issue using my faultmate. The O2 readings where exactly as yours, one staying static no matter what I did. It wasn't until I tested the outputs with a multimeter that I discovers the Faultmate was actually bugged. To be fair blackbox jumped straight on the issue and released a patch update but I wasted a long time chasing spooky readings.

Leak checking is best done with a smoke machine. Are you happy with your MAF readings ? I've got some known good readings somewhere if you need a reference, from memory at idle you should see 22 kg with all loads off. Also take a look at fuel rail pressure, again from memory I think this should be about 55 psi. Lastly consider checking the valve lift on each cylinder, maybe a dicky lifter ?
 
I've swapped o2's about and have proved Nanocom is working fine also the car runs so bad I'm sure I'm not chasing a ghost. MAF readings could be helpful. All injectors appear to fire correctly and I've witnessed fuel spray. Should of also stated I've cranked the engine over with the rocker covers off and all the valves are opening and shutting. Which brings me back to an air leak. All good info though guys it's making me go back over the steps I've done.
 
Here you go...
MAF readings. engine upto temp - all loads off.

Idle 680rpm - 22Kg
1200rpm - 32.5Kg
2000rpm - 55Kg
3000rpm - 92Kg.
 
Guys, When I had the heads refaced should the machine company faced the inlet ports so they still line up with the lower inlet manifold?
 
Right I've redone the valley gasket. I've run out of time tonight so only got as far as refitting the lower inlet manifold. The valley gasket was once again a right bitch to fit. It took lots of massaging to get the the bolt holes to line up. Once I got the holes lined up and the lower inlet torqued up I used a 0.05mm feeler gauge to see if I could get it to slide in any where. I have to report I'm not confident I've fixed the issue. The feeler gauge went up under the lower face (so above the valley gasket) until it hit the ridge in the gasket at both ends. I fear the machine shop has taken far to much material off when they faced the heads and now the inlet ports aren't square on to the head ports. So basically the heads are scrap. If the ports do seal I fear the compression ratio will now be to high and cause pinking. This will cause the knock sensors to start retarding the timing and the engine will be a gutless pile of ####ed **** without the power to pull the skin of a rice pudding. Problem is I won't know until I've thrown it back together for umpteen wasted time. Honestly with the valley gasket bent gently in to position, with one bank holes lining up the other banks holes are approximately half a hole to low. Hmmmm this could soon become a parts vehicle as I'm losing the will (and cash) to give a **** about it.
 
sounds strange & is a long shot but try fitting 2xcomposite gaskets this should solve your problem ;)
 
Easiest way to find a vacuum leak is a smoke test.might be lucky and your local tool hire may have one or failing that build your own from a can some baby oil and a glow plug.
 
Right the plot thickens. Slung it back together again tonight. Started it up and yep Dipply the bagoh****e turned up. So anyway I decided to burp the water system and have a look at what the Nanocom was telling. Sure enough nearside O2 sensor was reading stalled lean again. Anyway even though it was running like an old dog poo I kept it going as I checked the heater was getting hot when suddenly it coughed the rev's went up and then it went to dog poo mode again. So I went to look at what the Nanocom was saying and then suddenly she coughed again and started running like a swiss watch. Sure enough both 02 are happily swinging between 0 and 1 volts. Hmmm check the misfire counter and sure enough all 8 pots are present and firing correctly. Hmmmmm so now what? I can't believe its now fixed all by its self. So the only thing I can do now is wait till tomorrow when Dipley is stone cold and see if it starts in dog poo mode which will pretty much confirm its still an air leak issue with the head to inlet manifold gasket. The only thing I did notice is the battery voltage drops terriably when I crank the engine. I wonder if thats contributing to the dog poo syndrome
 
Have you checked the MAF readings yet ?
My 4.6 was getting reluctant to rev over 3000 rpm before it was laid up last April and decided to sort it out when it gets back on the road, which was this week.
When I started it, it ran like a bag of ****e, all over the place, so connected Nanocom and read the faults. It was showing a fault on bank 1 ( can't remember exactly what it said ), and the MAF was reading 15 on idle, couldn't check at at 3000 RPM as it wouldn't rev that high. No miss fires were logged. Fitted new Bosch MAF, reset adaptive settings and hay presto it runs like a dream. No faults found, O2 censors reading correct, and MAF readings are now 23 at idle and 96 at 3000 RPM. Your problem may be different but I hope it helps you buddy.
PS. If it is the MAF only replace with genuine Bosch.
 
Latest Follow up. Started from cold today with a new battery fitted. Dipply the Swiss watch turned up today. Running as sweet as a nut. No issues both 02's swinging as expected and creamy smooth with a good amount of go. So filled the tank, took her for new tyres and made sure I had my mobile and RAC card in my pocket. I've now done 50 miles without hic up. I hate it when things suddenly work without an explanation. Still all I can do now is suck it an see for a bit. As a side note baring in mind when I got up this morning I didn't expect to buy anything other than lunch I've managed to munch through 800 quid!!! 100 quid battery, 100 quid fuel and 600 quids worth of tyres. GULP the Missus is gonna withdraw bouncy bouncy privileges for months when she finds out!!!! Thanks for the ideas if the problem returns I won't be asking for any help. Instead I shall slam my genitals in a draw full of broken glass then a bucket of vinegar followed by ceremonial burning of myself. This has driven me absolutely bonkers.
 
Fingers crossed for you buddy.
Just think how boring life would be if you had a vehicle that was reliable and predictable. No fun at all !!!!
Cheers. ;)
 
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