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The numbers...

I have dropped the shift points to 5200rpm with the high ratio rockers until the new valve springs are fitted. After fitting the spacer, It's lost a whole lot if intake heat under boost but it's also lost a whole lot of boost. This mornings run was a max of 10psi with intake temps hitting 93°C this afternoon with a higher ambient temp we are only seeing 4psi boost but intake temps are way down only seeing 72°C.

Cylair is way down to 730 from 940 before the spacer. MAF hz have dropped a little from 10200 to 9200. I do have a belt issue but it's to tight rather than to loose. The pulley is cooking on the front of the blower. Will need to get a longer one pronto.

Looks like some major retuning is going to be in order.

edit: ignore the large variation in boost. I'm 99% sure it is because I'm only logging at 3hz in passive mode. I'll do some more logs without passive mode to get better data.

Now to sort out a wiring issue with the driver side headlight. There is a short somewhere, when the head lights are on the high beams on both headlights glow lightly and when you pull the high beam on it only the passenger side works

Just found an old 6pk1750 belt in the garage which is a much nicer fit than the 6pk1735 I was running.

Still no further with the headlight. I have it out now, tracing wiring trying to locate a short

I suspect the fault is in the headlight itself but it's an aftermarket sealed unit and I can't get into it without destroying it so it's hard to figure out what is going on in there as the unit has an extra relay fitted which has something to do with the high beams by the looks of things.

Where's all the boost and maf flow gone lol is the bypass not working properly with the spacer or got a crossleak somewhere

I'm thinking the bypass might be an issue. Some of the hard line type vacuum lines going to/from the boost bypass valve etc are very tight. I wonder if they are leaking? Might have to go and get some vacuum tubing tomorrow and remake those to ensure that is all ok.

Got it all back together, gave it a quick rev and the boost bypass valve doesn't seem to be closing properly. Will fit new vacuum lines and then re-test.

Do the diaphragms ever fail on the M90s? I had one fail on my old M112

brindo wrote:Do the diaphragms ever fail on the M90s? I had one fail on my old M112

In the bypass valve? They are known for failing. Most people bypass em so they stay closed.

Mine was working fine this morning. I think part of my problem is those hard plastic vacuum lines that don't like changing the angles they've been sitting at for the last 15 years.

Well it looks like the boost bypass valve is toast

Replaced the vacuum lines, got rid of the vacuum leak but still no better. Then bypassed the valve altogether and hey presto, got my boost back but with the bypass been closed all the time it's increased the IAT's too now seeing 80°C when cruising once everything is up to temp where as before it was ~60°C. Bugger it, going on a long road trip on the weekend so I don't think there is time to get a replacement valve anywhere.

And a pretty picture to go with it.

So I've done the boost solenoid bypass mod. Well see how it goes. The valve does seem to be moving now as it should but I haven't had a chance to log anymore as the missus has taken her car back