Problem with turbo response and boost gauge

[GreasyJoe]

IMG_2050sm.jpg

turbotransducer.jpg

Hi
firstly if you respond can you kindly state what I need to do where in simple terms as I've not spent much time under the bonnet and in the book to have an in-depth understanding of everything with these cars.

Background:
I've a 1992 Lotus SE Turbo which I've had just coming up to a year now.
The car is wanting in having work done to it though the engine has always seemed strong. Only 87k on the clock.
Early after buying the car I replaced all the three gauges as the backing when the lights were on was so badly crazed I couldn't read them. I replaced all with original new Lotus OEM items.
Also replaced at the same time was the air filter.

Firstly about 3 weeks ago, not driven 2 miles so engine was just warm; I was heading out on a dual carriageway and coming out off a roundabout gave it some wellie going up an incline. It accelerated fine as usual, feeling the turbo boost kick in but then it suddenly started lurching and loss of power under acceleration. The engine light flashed on! So immediately backed off and things settled down and I drove on. The engine light went out. Nothing more to report though I was keeping off hitting the turbo again.
Drove the car some days later just around the block and all seemed ok. Noted if I accelerated enough to get the turbo to normally 'kick in' that the boost gauge didn't move. Checked the car and noticed the vacuum hose to the orange transducer(?) on the right of the engine had come off so just pushed it back on.
I think this is for the gauge but does it do anything else relating to the turbo?

Went out in it a number of times since and its driving fine. No warning lights but the turbo doesn't feel to be kicking in as before. Previously was quite distinct around 2.8-3k rpm which I think is normal for a standard car, and the boost gauge would move up.
I wouldn't say it isn't accelerating ok but not feeling that turbo kick like before, or getting that excited sprint and torque steer I previously used to feel.

So things I've noticed since the incident:
1. Initially post the incident, the boost gauge needle would move up just past 0 when the ignition was on or whether the engine was running or not. Under acceleration it wouldn't do anything more, I assumed later due to the vacuum hose had come off it.
2. Checked the Earth wire on the transducer wasn't loose (had been before when I first had the car). It was fine.
3. After putting the vacuum hose back on and just ignition on or engine running, revving, the boost gauge now sits at like 2.5 bar - see pic.
4. Engine cold. Took the air intake hose off the side of the turbo to look for anything obvious issues. Vanes look ok, no play at all in the shaft. Turns easy.
5. Started the engine up with the intake hose off and can see the turbo is going around with no unexpected noises, and revving does look to increase its rev's. Not sure if I should be hearing any loud distinctive whine when I rev the engine when just in the driveway?
6. General inspection of hoses and pipes doesn't look like anything is untoward but not sure if I would spot certain ones in the first place. Most of the rubber hoses and pipes are well due for replacement. The gauge vacuum hose is looking a bit crispy but no obvious leaks as far as I can make out - I haven't taken it off for detailed inspection.

I did see in another post something about the waste gate rod? Can you say what it does and could it affect the turbo. Point me to its location and what manual inspection can be done?

So looking for suggestions regarding the gauge and the turbo, or anything that relates to them to check that can be causing issues?

Any advice will be grateful.

PS - anyone know of Lotus garages around North Oxfordshire/Warwickshire/Northant's are that do work on Elans?

[Tuga2112]

just to clarify.

as of right now. if you turn the key to the "on" position. but dont start the car.
does the boost gauge read zero or is it reading the same as in the picture ?

the wastegate wiggle (see the wiki) is something that is free to do, and has a chance to solve your issue of not getting any boost. (assuming the wastegate is stuck open)

what i'm most curious about what you describe is the gauge reading. which could be due to multiple different issues,

[HJ2]

It should be horizontal or zero.

I would start by checking the ground connection at the sender
Undo, clean the contacts and secure the screw & plug again.
If that does not help: check the ground wire with a multimeter or temporarely connect it to a ground elsewhere on the block for troubleshooting

Good luck!

[GreasyJoe]

just to clarify.

as of right now. if you turn the key to the "on" position. but dont start the car.
does the boost gauge read zero or is it reading the same as in the picture ?

the wastegate wiggle (see the wiki) is something that is free to do, and has a chance to solve your issue of not getting any boost. (assuming the wastegate is stuck open)

what i'm most curious about what you describe is the gauge reading. which could be due to multiple different issues,

Hi Tuga2112
yes it shows the gauge as in the picture though it has come down a little from the first marker on the face. it jumps up as soon as the key is in the on position.
further information when driving, when i push the engine up the rev's the boost gauge does rise so it is responding somewhat. There does seem to be some boost from the turbo though its much more subtle and gradual than before. Doesn't have that 'immediate' feeling of the boost kicking in. Seems much more gradual as far as i can make out.
I've just read the wastegate wiggle article and it does sound like it could be that if sticking it may not be allowing enough gases to get to the turbo and so be less effective. I'll have a go at doing it and see if it improves performance and maybe sort out the gauge at the same time.

the cars parts are a bit crusty in places though solid.
I did try checking some of the small hoses for any splits. The one to the transducer has a very crispy skin but looks to have no leaks.

Would be good to know what diameter some of these small hoses are. I seen Serco do a 3 piece kit but its like £70! I'd just be happy with some cheap alternatives I can cut to length instead.

[RonR]

I see you have a Dump Valve fitted, it might be worth checking it out. If the diaphragm gets stuck open it could affect the boost.

[GreasyJoe]

It should be horizontal or zero.

I would start by checking the ground connection at the sender
Undo, clean the contacts and secure the screw & plug again.
If that does not help: check the ground wire with a multimeter or temporarely connect it to a ground elsewhere on the block for troubleshooting

Good luck!

Hi HJ2
yep, it was acting fine reading dead on zero (is a brand new original gauge been on the car less than a year)
just happened after the cough and splutter I had when pushing the car hard that time. then afterward I started to notice the gauge was not on zero.
When I first got the car and the old gauge I had a bad ground connection with that wire so have previous cleaned and tightened it up. was happy after and with the new gauge, but its worth checking it against the block or other good ground location for sure.
thanks for your advice. I'll keep checking. maybe the wastegate wiggle might help me out too. like I mentioned some of the components are a bit crusty even though the engine is fine (usually) and pulls strong.

Also got component parts from mouser electronics to make up an elan scan cable just need to get the solder iron out and finish it off. probably scare me with all the readings once its up and running
I initially made the mistake of buying a standard (opal?) cable off ebay after watching the youtube channel about it. found all but one of the pins had a wire and it was one that was needed. being a moulded socket I had to try opening it up to see if I could re-wire it but after hacking at it there was no way I could have used it.

[GreasyJoe]

I see you have a Dump Valve fitted, it might be worth checking it out. If the diaphragm gets stuck open it could affect the boost.

ah ignore the engine bay picture. I just nicked it off the net to indicate the orange transducer thingy.
My engine is all standard turbo. not mods as far as I know.
I'll take a pic of mine just to show but its really grubby site to see

[Tuga2112]

id suggest to remove both wires at the transducer end. and clean their connections throuly and refit.
then turn the key again and check if the boost gauge is on the zero or if it moved up again.

if that is still moving up.
disconnect the wires. and with the key on, check the voltage across them with a multimeter.

i wonder if there is something else tapped into that circuit that shouldnt be there.

also check what is the gauge reading when both wires are disconnected. (again should be zero)

[GreasyJoe]

id suggest to remove both wires at the transducer end. and clean their connections throuly and refit.
then turn the key again and check if the boost gauge is on the zero or if it moved up again.

if that is still moving up.
disconnect the wires. and with the key on, check the voltage across them with a multimeter.

i wonder if there is something else tapped into that circuit that shouldnt be there.

also check what is the gauge reading when both wires are disconnected. (again should be zero)

Thanks Tuga2112, will do. fingers crossed the weather is kind this weekend. No garage unfortunately.
By the way I assume its your youtube channel? Really good vids. subscribed

My car is on youtube if you want to view it. just a chance meeting with the guy at a local car meet. Not entirely sure why he picked mine. its not the best example, though it did behave itself on the day, mostly lol.
https://youtu.be/EaaopxfJMu4

[GreasyJoe]

Update - in between the snow, rain and wind was out on the car today being nice weather.

Not sure why I started with the wastegate, wish I hadn't really. Hassel of taking off the third bolt holding the wastegate plate to the turbo housing was a pain. Finally got it off, but to try and get at the circlip at the other end I had to take off the heat shield. Had avoided it due to the bolts being so tight and two out of three virtually inaccessible. Got it off eventually. nearly took most of the day doing it. Then noticed the other lower heat shield still covering where the circlip is. Just one bolt too many. Thing wont budge.

So having the wastegate loose, with it only attached at the circlip end, its hose off, I wiggled it as much as I could in all directions hoping that will be enough to free it up if it was ever stuck in the first place. It seemed pretty movable.
Finally went to put the heat shield back on but had to give up for the day. The two side bolts are a nightmare. Virtually only can be done by feel and fingers. And can I line it up with the holes! Have the car jacked up for the left one as its the only way to undo it let alone get the thing back in place. Hopefully I may be lucky tomorrow and they all align first time. Any tips on getting these things in place welcome!

One good thing though. Found why the boost gauge is sitting off the zero mark. Wire on the transducer screw though tight was earthing badly. After getting it all off found both wire and plate was rusty. I think there must have been some current getting through but hardly. Was stopping the boost gauge going up to max. Managed to get the transducer off. The rubber nuts were in a mess and was a struggle getting them off too. Will need replacing. Sanded down the rusty surface and clamped the wire to the transducer body. Boost gauge back to normal.

Once I get it all back together I'll finally be able to see if the turbo is behaving or not. I hope it is.

All I got to say is the guys who designed this car must have been sadists lol

I love the car but the work I need to do on it may be too much for me. I don't have the facilities and didn't realise how much was involved in working on this car. Watch this space as I may be selling it soon

[GreasyJoe]

HI again,
So as mentioned below the boost gauge is sitting on zero as it should now. I also replaced the two small vacuum pipes, one going to the transducer and another just adjacent to it, same size on the engine. The originals were pretty crispy and the one on the transducer when I revved the engine popped off!
So all seems to be back as it should but now driving, the boost gauge hardly moves if at all. Have to accelerate hard even to get any sign its reacting. Going through the revs nothing happens until after 4k on to 5k rpm before the needle moves and only a little for a very short time. Aside from if the new gauge is working or not (no reason why it isn't), more importantly there's no feel of the previous turbo kicking in at a much lower in the rev rang around 3k. No kick in acceleration or torque coming through the steering like it did before as kept accelerating hard. Only getting the revs really high does the torque feeling come through the steering, but that could just be coming from the engine without the boost? The car still accelerates well but just doesn't feel like the turbo is kicking in much if at all especially at the lower rev range, which seems to match the boost gauge read out.
Previously I'd checked the turbo spindle for too much play and it felt fine. The wastegate moves ok when I was wiggling it. The short vacuum pipe at the end of the wastegate looks ok, no obvious leaks.

Anyone suggest for anything else, any other item to check that may be hidden away? Another hose popped off or leaking?
Could there be a completely different component that could affect the turbo? Is there any electronic component that manages the turbo? I'm at a loss really.

Only saving grace, even as it is now, it went through the MOT fine. Both times since owning the car. I'm really getting to the point of selling it on to someone with more knowledge about these cars as its starting to get too much hassle.

Update - in between the snow, rain and wind was out on the car today being nice weather.

Not sure why I started with the wastegate, wish I hadn't really. Hassel of taking off the third bolt holding the wastegate plate to the turbo housing was a pain. Finally got it off, but to try and get at the circlip at the other end I had to take off the heat shield. Had avoided it due to the bolts being so tight and two out of three virtually inaccessible. Got it off eventually. nearly took most of the day doing it. Then noticed the other lower heat shield still covering where the circlip is. Just one bolt too many. Thing wont budge.

So having the wastegate loose, with it only attached at the circlip end, its hose off, I wiggled it as much as I could in all directions hoping that will be enough to free it up if it was ever stuck in the first place. It seemed pretty movable.
Finally went to put the heat shield back on but had to give up for the day. The two side bolts are a nightmare. Virtually only can be done by feel and fingers. And can I line it up with the holes! Have the car jacked up for the left one as its the only way to undo it let alone get the thing back in place. Hopefully I may be lucky tomorrow and they all align first time. Any tips on getting these things in place welcome!

One good thing though. Found why the boost gauge is sitting off the zero mark. Wire on the transducer screw though tight was earthing badly. After getting it all off found both wire and plate was rusty. I think there must have been some current getting through but hardly. Was stopping the boost gauge going up to max. Managed to get the transducer off. The rubber nuts were in a mess and was a struggle getting them off too. Will need replacing. Sanded down the rusty surface and clamped the wire to the transducer body. Boost gauge back to normal.

Once I get it all back together I'll finally be able to see if the turbo is behaving or not. I hope it is.

All I got to say is the guys who designed this car must have been sadists lol

I love the car but the work I need to do on it may be too much for me. I don't have the facilities and didn't realise how much was involved in working on this car. Watch this space as I may be selling it soon

[FunElan]

Do you hear the whistle at all? You should be able to feel boost if you floor it in 2nd gear. It should be obvious, at least it is in my car.

Maybe you need to check for boost leaks. You could use a bike pump and pressurize the system as mentioned on here. Or maybe a smoke test. Haven't read the whole thread, but do you have access to elanscan? It'll tell you if it's boosting

[GreasyJoe]

Hi, thanks for your reply.
I wouldn’t say so regarding either. Maybe very little when accelerating right at the top end there’s something. Thing that obvious compared to how it was. I’ll need to give it a run again but just to check.

Yes I’ll have another look around the turbo for leaks. One of the heat shield bolts which sits between below the engine and engine mount I couldn’t get back on last time. Any chance that could cause a leak?
I don’t have an elan scan. I do have the components to make the cable and downloaded the software so may have a go at building that. Be worth getting the readings

Do you hear the whistle at all? You should be able to feel boost if you floor it in 2nd gear. It should be obvious, at least it is in my car. .

Maybe you need to check for boost leaks. You could use a bike pump and pressurize the system as mentioned on here. Or maybe a smoke test. Haven't read the whole thread, but do you have access to elanscan? It'll tell you if it's boosting

[TorqueHorse]

Heat shield bolt would have no impact to your boost. But I agree with FunElan on double checking that all your hoses along the entire run are snug up. Especially if you were knocking around the turbo before for the wastegate and heat shield, you may have knocked something else loose unintentionally. If you want to understand how the boost system works on the Elan (In what I think is more easy to understand language than the workshop manuals) you can learn more from https://elanchips.co.uk/ (even if the mountain chips aren't available anymore, the content there is great)

[GreasyJoe]

Thanks for the advice TorqueHorse. Yes it feels like that. It’s tight working around it so could have disturbed something. The hoses are in need of replacement so may have a leak. Will definitely read up the boost as don’t have any knowledge about turbos. Was out again today and tried giving it the beans and got the boost gauge to move a fair bit but it only did it high in the rev range and even then no real turbo kick I previously had even though the performance was good.

Heat shield bolt would have no impact to your boost. But I agree with FunElan on double checking that all your hoses along the entire run are snug up. Especially if you were knocking around the turbo before for the wastegate and heat shield, you may have knocked something else loose unintentionally. If you want to understand how the boost system works on the Elan (In what I think is more easy to understand language than the workshop manuals) you can learn more from https://elanchips.co.uk/ (even if the mountain chips aren't available anymore, the content there is great)

[esprit888]

When you say you got the gauge to move 'a fair bit' what was the reading in bar (0.4 ?) don't expect it to go past halfway even with your foot planted. Also you referred a few times to the 'Vacuum' line to the transducer blowing off, that's because its not a vacuum, its a pressure (boost) line. Its possible the car went into over boost shutting the fuel off if the wastegate was stuck closed. This can also blow off other hoses causing low/no boost but i would expect you could hear that. Worthwhile checking all the larger hoses from the compressor side of the turbo to the intake manifold, especially the two connections to/from the intercooler under the LH front tire as these can blow off but remain in close proximity to the pipe giving some boost, but very little.

[dapinky]

The easiest way to establish if you have a vacuum pipe off is to run the car at idle, then deliberately remove an easily-accessible hose. You should hear the engine speed drop before picking up again and settling very slightly higher than you started as the sensors try to make up for the sudden changes in pressure in the manifold.

If you don't get any change at all, then it in an indication that there is already a 'leak' so the sensors don't have to do anything.... all you then have to do is find the leak & fix it!

[GreasyJoe]

Hi Dave. Thanks for the advice. Sounds the best way to start investigation. Sorry to sound a bit thick but can you recommend a particular hose?

The easiest way to establish if you have a vacuum pipe off is to run the car at idle, then deliberately remove an easily-accessible hose. You should hear the engine speed drop before picking up again and settling very slightly higher than you started as the sensors try to make up for the sudden changes in pressure in the manifold.

If you don't get any change at all, then it in an indication that there is already a 'leak' so the sensors don't have to do anything.... all you then have to do is find the leak & fix it!

[dapinky]

Hi Dave. Thanks for the advice. Sounds the best way to start investigation. Sorry to sound a bit thick but can you recommend a particular hose?

It really doesn't matter - but probably the easiest one is the pipe between the turbo sender unit on the drivers inner wing and the inlet manifold - at least you can see and feel the whole thing!

[GreasyJoe]

Cheers!

Hi Dave. Thanks for the advice. Sounds the best way to start investigation. Sorry to sound a bit thick but can you recommend a particular hose?

It really doesn't matter - but probably the easiest one is the pipe between the turbo sender unit on the drivers inner wing and the inlet manifold - at least you can see and feel the whole thing!