[engine_work] Xu9j4 Mi-16 Rebuild

[kyepan 291]

Checked all of that and more.... And now I'm convinced it's just me hearing it coming on cam! When given full beans you can hardly hear it and it just sounds like a progression of the induction note.

 

425 miles.

 

Cheers

 

J

[Tom Fenton 1,526]

Have you checked the cam pulley bolts, I have had one come loose before, to the extent that it was out touching the cam cover. Luckily I found it before the engine did itself a mischief. It sounded like quite a faint rattle, this was the washer rattling about as it was loose.

[kyepan 291]

Have you checked the cam pulley bolts, I have had one come loose before, to the extent that it was out touching the cam cover. Luckily I found it before the engine did itself a mischief. It sounded like quite a faint rattle, this was the washer rattling about as it was loose.

that was on my second list, so i'm glad you mentioned it, paul also mentioned it when we chatted the other day. I may look at that on saturday, it only takes ten minutes to pull the cam cover off.

 

Cheers

 

J

[Tom Fenton 1,526]

I would definitely check it before you run it again. The cover doesn't even have to come all the way off to get a spanner in there.

[kyepan 291]

I would definitely check it before you run it again. The cover doesn't even have to come all the way off to get a spanner in there.

 

I'll test that theory tonight!! if so thanks you've saved me some hassle. May also take one of the cam caps off on saturday to reset the oil seal, as it's not happy, and is leaking slightly.

[kyepan 291]

have ordered two new cam oil seals just in case, if they are fubarred.

[kyepan 291]

Have a vibration at 5500 rpm, that lasts till 6250rpm. sounds loud enough to be something engine, touching on something chassis. or something connected to the engine, touching something chassis, or something large and plastic / metal, that is loose.

 

It was the cam cover, the back captive hex bolt that holds the large cover on, was being a pain and has come undone. It was touching the fuel filter and generally not secured. It is now. No more vibration.

 

Cam pulleys checked out ok too.

 

Happy again.

[petert 554]

Glad to hear it's sorted. Looking forward to the video shot over the driver's shoulder shot as you hit the rev limiter. 2nd gear will be fine.

[kyepan 291]

Hi there,

 

Got the car on the rollers, did a few runs, made 169.7 bhp corrected at the fly, reasonably happy, here are the graphs.

 

note the wobbly bit is the slight loss in signal from the rpm sensor

 

then we remembered the lambda probe was not in and did some with the AFR at which point we realised it was running dangerously lean. Rich at idle, super lean through the mid range (where it was noticeably down on torque 40ftlbs on paul's gti-6 engine) then it only richened to somewhere near normal towards the redline

 

Comparing to Paul's engine, where the AFR was somewhere in the middle of the graph, mine is up in the top quarter… to right at the top.

 

 

Also the cam shaft oil seal is leaking a noticeable amount of oil, so cams will have to come out again to do that properly, or at the very least - belt off, pulleys of. take the old ones out and put the new ones in. But i think it will be cams out because i want them sitting right.

 

I am happy with the initial power figure, but clearly there is more to come, especially in the midrange.

 

Plan is now.

 

1)Check TPS to make sure full throttle enrichment is working - will back probe for resistance in situe, and probe at the ecu to make sure the loom is ok.

 

2)Run again with the fuel pressure gauge on to make sure that the pump is supplying 3.0bar under load.

 

3)Possibly change the fuel filter if the pressure is not up to scratch - as that's not been done in a while (i don't know when it was last done)

 

4) Change the pump to an after market wallbro pump if the filter does not fix.

 

5)About AFM, I re-tracked it a couple of years ago, it made no difference, as the resistance values were already within tolerance. And with the fuelling so far out, especially where the afm will be open circuit, i'm doubting it is to blame - initially. If anyone has a spare afm handy i could borrow that may help.

 

6) ECU - This is last on my list, I trust integrated circuits more than the other mechanisms for supplying fuel. Thankfully i have three row, that will wind the ignition off if it detects detonation.

 

 

So, after feeling like the work is done on the engine, i have a tricky leak and some tuning / fault finding to do before the engine will give it's true power figure. Thought this would be the easy bit. he he.

 

J

[Tom Fenton 1,526]

So, after feeling like the work is done on the engine, i have a tricky leak and some tuning / fault finding to do before the engine will give it's true power figure. Thought this would be the easy bit. he he.

 

Easy or not, these are the bits that will transform an average engine into a good engine, keep at it.

 

Given that you have done some work to the engine, it may be that there is nothing wrong with the fuelling, it is working to fuel a standard engine but isn't quite the job for yours. Have you had the injectors checked recently? A bit of a bodge/get round but a bit more fuel pressure should move the whole fuelling trace down a bit.

[kyepan 291]

Easy or not, these are the bits that will transform an average engine into a good engine, keep at it.

 

Given that you have done some work to the engine, it may be that there is nothing wrong with the fuelling, it is working to fuel a standard engine but isn't quite the job for yours. Have you had the injectors checked recently? A bit of a bodge/get round but a bit more fuel pressure should move the whole fuelling trace down a bit.

 

Thanks

 

We did discuss a spare adjustable regulator that is floating around amongst paul's friends, as an option.

 

But, in the mean time I'm going to treat it as an engine management issue, and disprove that theory first.

 

It might bring it a bit more within tune to use the regulator, but i'm not sure how it's going to affect idle / cold start.. inevitably this conversation moves towards proper stand alone management..

 

It's also got PeterT's chip, that should fuel it for the cam, which made me rule out the lack of fuel being down to.. a hungry engine.. but i'll bear that in mind.

 

cheers

J

[petert 554]

It should drop under 13:1 under full load. Have you serviced the injectors lately? The fuel table in the chip is stock. The extra power & torque comes from revised ignition values. So if you haven't got 3 Bar at WOT, or the injectors are dirty, you will run lean. If the AFM has been tampered with, that's another issue, but I'm not sure that if that would effect WOT. There is enough fuel in the standard injectors @ 3 Bar for 180/185hp.

[Anthony 1,000]

As said, keep at it as it looks like there's more to come both when the fuelling issue is addressed and as the engine loosens up more

 

Looking at the AFR trace it's not as bad as it sounded in your text yesterday - it's certainly on the lean side for maximum power, but it's pretty much always below 14.2:1 so I wouldn't call it dangerously lean personally - certainly I can't see you melting anything.

 

I would suggest that it's not an issue with the pump or filter, as both of these would IMO tend to get more restrictive as the revs (and thus demand for fuel) increases, and thus you'd expect it to be senisble AFR's at lower revs and get leaner as they increase - which clearly it isn't doing. Indeed, from memory you had a typical knackered Phase 2 pump previously didn't you that exhibited that behaviour, showing itself as being flat as a pancake at top end. Either way, double checking fuel pressure as suggested above will confirm one way or t'other.

 

As I said, I'd double check that the TPS is working correctly and that it's correctly telling the ECU that you're at WOT - I've not tried it on an Mi16, but certainly on an 8v (which uses the same switch) it's very obviously down on power and lean when the switch isn't working/connected, and all the switches are getting old and knackered these days. I'm sure Petert will confirm, but from memory Motronic has a seperate WOT fuelling table and this won't presumably be getting triggered if the TPS isn't working properly.

 

Given how happy you are with the engine as it stands, you should be in for a treat when it's giving its full potential

[petert 554]

Yes, there are separate WOT maps for both ignition and fuel.

[kyepan 291]

Tested the Throttle Position Switch by back probing and it works at the switch end. Will need to go out again and do the ecu.

 

One side note - i also adjusted up the throttle cable a little, and noticed the idle behaviour change markedly... Now, with the cable adjusted up, it will take an age to settle down to idle revs, but will idle totally normally if left to it's own devices. when cold it is more noticable, when hot it's not as noticable.

 

Just need to test fuel pressure now.

 

Incedentally, Caps, says, fuel pressure under load can be 2.8-3.2 bar.. so there is a variance.

Edited January 19, 2012 by kyepan

[Tom Fenton 1,526]

One side note - i also adjusted up the throttle cable a little, and noticed the idle behaviour change markedly... Now, with the cable adjusted up, it will take an age to settle down to idle revs, but will idle totally normally if left to it's own devices. when cold it is more noticable, when hot it's not as noticable.

 

Sounds like the cable is just holding the TPS from the "idle" switch point.

[petert 554]

You should be able to here the TPS contacts "click" as you move it off idle if setup correctly.

 

Yes, that is the normal tolerance. I always look for regs. on the high side. At idle, they'll read 2.2-2.4Bar however.

 

To check volume delivery, disconnect the return pipe from the fuel regulator and place it in a bucket. It should fill > 540mL in 15 secs.

Edited January 20, 2012 by petert

[wicked 103 3 Cars]

Did you test the TPS by hand or flooring the pedal? Could make significant difference.

 

The mechanism that opens and closes the lower valve of a D6C throttle body sometimes wears out and the valve might not close properly when releasing the throttle.

The DFW has a slightly different mechanism.

 

Nice project btw.. I'm following it already for while, since I'm also rebuilding a Mi16.

Edited January 20, 2012 by wicked

[kyepan 291]

Did you test the TPS by hand or flooring the pedal? Could make significant difference.

 

The mechanism that opens and closes the lower valve of a D6C throttle body sometimes wears out and the valve might not close properly when releasing the throttle.

The DFW has a slightly different mechanism.

 

Nice project btw.. I'm following it already for while, since I'm also rebuilding a Mi16.

Good point I'll look at that as well, good luck with the engine build, do you have a build thread?

[kyepan 291]

Evening, a quick update.

 

So because I rushed the refit of the lifters and didn't spend the hour minutes it would have taken to slacken off all the cam bearing caps to get the oil seals seated perfectly, I took Saturday afternoon to take the cam belt off and replace them five and a bit hours in total. Still, it doesn't leak now. But the exhaust centre box is now blowing.. Need another centre section.

 

Secondly, it's definitely lean. When it was tight and new ther ewas clearly enough fuel and it sounded deeper and better and angrier. Now it's loosened up you can just hear its not right. Took Paul for a quick spin and he said it sounds hollow. I think the motronic is winding back the ignition too as it kind of hesitates very slightly..

 

So plan is as above really, check its on pressure under load, change the filter and possibly test a few other components if necessary until it sounds right and goes right. Paul also mentioned that regulators sometimes fail. In the mean time I'm just going to bumble about, ticking a few more miles over.

[maxi 36 1 Cars]

I personally do not know a sausage about mapping and have never tried it, however, I was told by a very knowledgeable bloke who has probably several years worth of constant rolling road and mapping time under his belt that, lean engines can make slightly more power (NA and obviously not lean enough to melt something). He told me this from his many years experience as a mapper and rolling road operator.

 

The motronic can be a wanker of a thing sometimes and can really make an mi seem slow and as you describe "hollow". Some people have said to me how s*it and slow an mi engine is and they want to swap the unit as theirs is obviously knackered. I have had experience of changing worn out connectors, AFM's etc to these units, only to bring them back to the limiter lickers they once were.

 

Im not doubting your mechanical knowledge/skill here but you do have the cam timing spot on dont you? So many people seem to time them up to the std marks and yet the engine underperforms. Whilst others do the same and its a rockett ship. Back in the day (and I will be shot down for this but this theory/hypothesis never failed), if the cambelt whined, you had a quick one. My original mi whined and absolutely flew, as with the others that had slightly more tension on the belt, they definately seemed to shunt.

 

I personally think you deserv a pat on the back, youve done brilliantly here.

 

Maxi

[Sandy 189]

Optimum mixture does vary between engines/specs quite alot and through the WOT rpm range in every case; but most mappers work to fixed AFR values throughout. Unless you have alot of data on what's good and will be reliable, you need to be very careful. Engines that can run safely leaner, will run cleaner and tend to keep performing longer as a result, "wet" set up engines deteriorate and the rate of decline is epicyclic as the rings and bores get worse. In this case I would not be frightened by 14:1 WOT, as long as the ignition map isn't too edgy.

[kyepan 291]

lean engines can make slightly more power (NA and obviously not lean enough to melt something). He told me this from his many years experience as a mapper and rolling road operator.

Optimum mixture does vary between engines/specs quite alot and through the WOT rpm range in every case; but most mappers work to fixed AFR values throughout. Unless you have alot of data on what's good and will be reliable, you need to be very careful. Engines that can run safely leaner, will run cleaner and tend to keep performing longer as a result, "wet" set up engines deteriorate and the rate of decline is epicyclic as the rings and bores get worse. In this case I would not be frightened by 14:1 WOT, as long as the ignition map isn't too edgy.

Would be interesting to hear what peter has to say about the ignition map, as that's what's different in the chip.

I'll have to admit that i don't know what i'm doing at all with tuning either, so perhaps i should leave it alone, my will to tinker is very strong though.

 

 

The motronic can be a wanker of a thing sometimes and can really make an mi seem slow and as you describe "hollow". Some people have said to me how s*it and slow an mi engine is and they want to swap the unit as theirs is obviously knackered. I have had experience of changing worn out connectors, AFM's etc to these units, only to bring them back to the limiter lickers they once were.

 

First port of call is definitely some component swapping, perhaps a bit of ecu back probing too to make sure the right voltages are getting back to the ecu, based on your connector experience.

 

Im not doubting your mechanical knowledge/skill here but you do have the cam timing spot on dont you? So many people seem to time them up to the std marks and yet the engine under performs. Whilst others do the same and its a rockett ship. Back in the day (and I will be shot down for this but this theory/hypothesis never failed), if the cambelt whined, you had a quick one. My original mi whined and absolutely flew, as with the others that had slightly more tension on the belt, they definitely seemed to shunt.

 

It's funny that you mention this, as when you originally posted this opinion possibly about 4 years ago, it did stick in my mind, and i do err a bit on the tighter side.

 

There is some variance in the advance or retard you can get on an MI using the tensioners anyway with the balance of front and rear tension. Loads of front tensioner would definitely advance the cams a bit.

 

it would be an interesting if slightly geeky thing to test the actual amount of avance you could get using the tensioners for example peter t says

The results below are for a freshly rebuilt XU9J4Z engine. It had new pistons and liners, a fully reconditioned standard cylinder head. About as good as it gets. In the first run it was fitted with an offset key on the inlet camshaft to advance the inlet timing 4 degrees. This effectively takes the inlet lobe centre line from 111 deg. ATDC to 107 deg. ATDC. Many achieve the same by fitting vernier pulleys. This change makes the engine a lot stronger in the mid range , moving top end horsepower peak down a tad. With this modification the car is a joy to drive at 100-110km/h. It will overtake with ease in 5th gear.

 

We did spend a while adjusting the tension so they were bang on and the locking pins had some wobble when originally timing the engine. It just so happens i had to wind a bit more front tension on to get the front pulley sitting nicely with the locking pin giving a bit of wobble, when refitting the belt over the weekend, this actually made it whine a. The belt was timed up exactly the same as it was previously, its just had 500 miles on it since I last set it. Sounds like it may have stretched a little (a slightly contentious point i know).

 

 

PS thanks for the kind words.

Edited January 24, 2012 by kyepan

[petert 554]

You can only get approx 1º by playing with the belt. Valve timing won't be your problem. It sounds hollow because it is lean. Attached is a typical 3 row AFR with 4 runs. Two with a standard "161" chip and two with the chip you have. It doesn't look anything like yours. You really need to identify whether it's a pressure or flow problem, or a combination of both. As I said earlier, it's very easy to check for flow. Just plumb the return hose off the regulator into a bucket and run for 15 secs. That test will identify a pump problem. For example, it may be the small hose connecting the pump to the housing. Loose clamps & split hose are common issues that can't be seen. Testing for pressure is more difficult but you have to do it. Whilst it won't blow up at 14:1, it will never make good hp either. My experience of these engines is that 13.0 to 13.1 is best.

 

In regards to valve timing, please refresh my memory on what pulleys you're running. If you want to verify it, you should have 0.065" lift @ TDC on the inlet.

 

How much was shaved off the block?

Edited January 25, 2012 by petert

[kyepan 291]

I was thinking about asking if anyone had an AFR trace with your chip peter, so thanks for the great reply! Hopefully i'll get a chance to look at it on thursday.

 

I'm running #4 inlet and #2 exhaust, and have had the block refaced a bit, but i wouldn't say any significant amount removed desk height wise.