free hit
counters
Boost solenoid - Engine/Ancilliaries - The Lotus Forums Jump to content
Chillidoggy

Boost solenoid

Recommended Posts

Going the the boxes of bits I have, I pulled out the three Delco solenoids (EGR, throttle jack, boost) specifically because I wanted to know which was which. I noticed that my boost solenoid has a connection to the wastegate and the turbo compressor. But it also has another tube which has been blocked off.

Now when I looked at the parts manual, it seems that connection should have a filter at the end. As I understand it, the solenoid bleeds off air from the wastegate, but how can it do that if the connection is blocked? The car did show 1 bar on the boost gauge at full throttle, prior to me ripping everything to pieces, so I'm a bit curious.

Share this post


Link to post
Share on other sites

Upgrade today to remove Google ads and support TLF.

Hmmmm. So why is mine blocked off?

 

OK, here's a scenario: The boost solenoid fails, so the PO blocks the relief port, and resets the turbo wastegate to give 1 bar mechanical boost. Call me old Mr. Suspicious, but I cannot see any way the solenoid was operating with the port blocked.

 

Is there any way of testing the solenoid out of the car, as it's all in bits right now.

Share this post


Link to post
Share on other sites

Testing is easy: rig the intake to a (low) pressure supply, connect 12V to the solenoid and check for escaping air. There should be none without the 12v supply.

Share this post


Link to post
Share on other sites

My boost gauge has gone all 'floppy' it sets at rest far over to the left of gauge, but when boosting i am only seeing .5 bar (but i know by the feel etc that it is fully boosting so no problem there) anyone have any ideas,maybe the gauge has just died?

 

 

Hmmm come to think of it when the car over boosts which does happen occasionally the needle flicks like a mad thing.....so i'm thinking busted gauge.

Share this post


Link to post
Share on other sites

The gauge in the dash gets its signal from the boost transducer tucked up under the bodywork by the right side fuel filler.

 

There is a rubber hose from the plenum (white line here) 

post-15426-0-65677400-1369939298.jpg

 

So it could be that the rubber hose that connects the hose to the transducer is cracked.

Rubber elbow shown here is to the MAP sensor BTW, the boost transducer is attached to this same plate.

 

DSC02545.JPG

 

It could also be the electrical connector to the dash gauge.

Share this post


Link to post
Share on other sites

I've not seen that plate either. From memory mine was just floating about above the rhs fuel tank!

Share this post


Link to post
Share on other sites

No, it is bolted up in the buttress behind the right quarter window, next to the solenoid to open the fuel door. There are two bolt heads that you can see through the body when the hatch opens.

Share this post


Link to post
Share on other sites

Found it,it is behind the r/h quarter light panel sits almost on the tank,vac pipe was in good condition ,electrical connections and wire really shabby (looks like heat damage),but gauge does flicked when pulling connector off ,so i,m erring towards a bad transducer.may take it off whilst repairing wiring and give it a technical clout ,if i bridge the two connection's will the gauge just go to full deflection does any one know??

Share this post


Link to post
Share on other sites

Gauge should go full one way with voltage, and full the other way when shorted to ground.

 

So maybe you just had bad wiring, I bet the gauge in the dash is fine.

Share this post


Link to post
Share on other sites

Ok have trouble shot the boost gauge by shorting to ground and the gauge only flicks half way ,so  as i suspected the gauge is broken,now for a search now for another one.Unless anyone has a spare ?

Share this post


Link to post
Share on other sites

Update,fitted second hand 'new' gauge works a treat,also heli coiled errant engine mounting bolt,what a diffence a tight engine makes! I really should hang my head in shame for not addressing earlier.

Eta.Spelling and various words missing.

Share this post


Link to post
Share on other sites

Back on course, I've just checked the boost solenoid. I removed the blocked-off rubber pipe from the bleed connection, put the pipe that comes from the compressor to solenoid in my mouth, blew through it, and air escapes through the bleed port that should have the sponge on it. There was not a lot of resistance at all. That is without any electrical connection.

 

I don't think it should do that, should it?

Share this post


Link to post
Share on other sites

Update: just tried 12v across it, and the solenoid clicks.

When I try blowing through the input tube with power on it, I can't, it's like it's been shut off. I haven't tried any compressed air at 14psi, though. But it seems 'not right' that I can blow through it at all.

I measured the resistance at 23 ohms.

Share this post


Link to post
Share on other sites

When the solenoid is de-energised the air flows from the compressor housing to the wastegate actuator port.

 

When the solenoid is energised the air flows from the compressor housing to the vent port.

Share this post


Link to post
Share on other sites

OK, but which port is which? I have no idea whether it was piped up correctly when I bought it!

Share this post


Link to post
Share on other sites

When viewed from the rear, as installed, the inlet port is at the top and the port closest to the wastegate actuator is the wastegate actuator port.

Share this post


Link to post
Share on other sites

Thanks Derek.

 

So given that information, the dump port on mine was definitely, and deliberately, blocked off. And if I'm right, then the effect of that would be that the solenoid would be unable to control boost over the wastegate mechanical setting. I did witness 1 bar on the dashboard boost pressure gauge, so I can only imagine that some previous individual had jacked up the wastegate rod until that pressure was reached.

 

But why would they do that? It sounds a bit dubious to me.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


×