think im overboosting

POE · Post by **POE** » Wed May 20, 2009 5:41 pm

it seems that when giving open throttle it is going to full boost in 1st and 2nd gear which i dont think it is supposed to and third gear it does not go into red even when upto 5000rpm ,but other times it wont go into red in the lower gear???

89 turbo running richmod, also forge dumpvalve fitted if helps.

B18FT - LOVER · Post by **B18FT - LOVER** » Wed May 20, 2009 7:17 pm

Hmm, have you tried removing the dump valve ? Try it see if it makes a difference, failing that iwould say it could be a ecu fault..

What colour are your ecu's bud, i have a spare orange if you want to try it...

POE · Post by **POE** » Wed May 20, 2009 7:36 pm

i thought about changing dumpvalve which ill do 2morrow with the standard plastic one,how about boost solonoid valve?

B18FT - LOVER · Post by **B18FT - LOVER** » Wed May 20, 2009 7:48 pm

Could be mate, its the map sensor, the one with 3 pipes init... I have a spare one of those too if you wanna try it...

Thinking about it now, a map sensor controls turbo pressure/manifold pressure so it would be a good possibility that it is that...

Either way, try ur dump valve first as i had a forge one on my rover turbo and it made it do all sorts of funny things, i removed it and problem gone...

I have a spare boost ecu and and map sensor - 3 pipe one... Cud try it, ill need them back thou

POE · Post by **POE** » Wed May 20, 2009 7:54 pm

i have a spare boost controller so try replacing them first ,and thanks for the offer .

A TRUE GENT.

B18FT - LOVER · Post by **B18FT - LOVER** » Wed May 20, 2009 8:04 pm

Careful you dont snap the little pegs off when removing the clips, basterd little things, and no worries for the offer any time....

Rapid-R5 · Post by **Rapid-R5** » Wed May 20, 2009 11:23 pm

The MAP sensor doesn't have 3 pipes, its inside the boost/ignition ECU and only has 1 pipe.

steve

B18FT - LOVER · Post by **B18FT - LOVER** » Thu May 21, 2009 6:39 am

Wrong - check a haynes manual, clearly says map sensor..

chris1roll · Post by **chris1roll** » Thu May 21, 2009 7:08 am

B18FT - LOVER wrote:Wrong - check a haynes manual, clearly says map sensor..

Sorry mate, but in that case the haynes manual is wrong, the map sensor on a turbo is inside the ECU, and the bit with three pipes going to it bolted to the bulkhead is the boost control solenoid.

dave r5 · Post by **dave r5** » Thu May 21, 2009 7:48 am

was gona say that the boost solanoid shudnt affect it. mine not even plughed in,

my ecu was modded so i dnt use it is this not the same with the rich mod

POE · Post by **POE** » Thu May 21, 2009 7:36 pm

well took it out once again 1st goes 3/4 into yellow 2nd into red and i held it on and it didnt cut out then 3rd into red but struggled a bit and 4th into red again ,didnt have chance to go to 5th as ran out of road(private road of course) any ideas to check ,havent had chance to change either dump valve or solonoid valve ?

chris1roll · Post by **chris1roll** » Thu May 21, 2009 7:50 pm

Ok, got a bit more time now...

The boost control solenoid - the three pipes that come off of it:

If any of these pipes are split or have a pinhole in them, then they will act like a bleed valve and give you the boost spikes you are experiencing. The usual culprits are the white or black ones at the ends you can't see - basically the pipes are too short and they split where the jubilee clamps bite into them. Solution - new, longer pipes, just get some silicone hosing off of e-bay to replace them with.
Secondly the red pipe can rub on the heater hose and wear through.

Even if the boost control solenoid is not connected electrically, or if you are running an entirely different system, if you get holes in the pipes that control the wastegate actuator you will get spikes.

Chris

POE · Post by **POE** » Thu May 21, 2009 7:55 pm

do you think its worth changed the dumpvalve to the plastic one or would that not be the issue?and are you saying that even if the boost controller was not working electrically it would not cause boost spikes?

chris1roll · Post by **chris1roll** » Thu May 21, 2009 9:18 pm

I would put the stock recirc valve on, the B18FT doesn't really like atmospheric dump valves....its certainly worth a try...

if the boost controller was not working electrically it would not cause boost spikes?

Double negatives!?

Even if the boost control solenoid was not connected electrically, if there are splits in the pipes you will still get spikes.

Explanation:
You could run a pipe direct from the pressure side of the turbo to the wastegate actuator, and boost would be set by the strength of the spring in the actuator (diesel engines are like this) I believe the actuator on the 480 has a 4psi spring. i.e. it requires 4 psi to work the actuator.
In this situation the engine will only run at 4psi, any more and the wastegate is opened.
Now, make a hole in that pipe.
The engine is running 4 psi, but 2 psi is bleeding off through the hole.
Only 2 psi is getting to the actuator so it isn't opened.
The engine is now running 6psi, you are still bleeding 2psi off through the hole so 4 psi is getting to the actuator and it opens. The engine is now running 6psi.
This is how a bleed valve works - its a rather crude way of doing things to be honest.
A MBC or manual boost controller works by physically restricting the amount of air going to the actuator, also a rather crude method
both the bleed valve and MBC are prone to spiking.
The solenoid bleeds off a variable amount of air and returns it to the cold side of the air intake, the remainder going to the actuator. because it is electronically controlled it can precisely control how much air is bled off to avoid spiking. if you have a hole in one of the pipes, allowing z pressure to escape, the solenoid will be told by the ECU to bleed off y amount of x pressure, but only x-z pressure arrives. It bleeds off y amount as instructed but because there is less than there should be the actuator doesn't get opened and boost increases - spiking - then the ecu sees the higher boost and tells the solenoid to bleed of more air to reduce the boost, which it does, and so on.

chris1roll · Post by **chris1roll** » Thu May 21, 2009 9:23 pm

chris1roll wrote:
B18FT - LOVER wrote:Wrong - check a haynes manual, clearly says map sensor..
Sorry mate, but in that case the haynes manual is wrong, the map sensor on a turbo is inside the ECU, and the bit with three pipes going to it bolted to the bulkhead is the boost control solenoid.

And anyway, didn't you buy mine off e-bay? I'm sure I sent it to Barnstaple (to be honest I could have dropped it off in my lunch hour!) I clearly advertised it correctly as a boost control solenoid.....

Edit2 - yes, you did

Think you got a bargain there at Ã‚Â£2.99 all in!

POE · Post by **POE** » Thu May 21, 2009 9:25 pm

superb explanation ,thankyou, i shall check all of these pipes as i have had them off recently.

chris1roll · Post by **chris1roll** » Thu May 21, 2009 9:36 pm

No probs, it is a common problem - like common as in they all do it eventually!!

pipes as i have had them off recently. Wink

aha!

However, reading again, are you sure you are over boosting - you will get into the red at high rpms in the lower gears, its if you get high boost at low rpms (as can happen when spiking)that you'll get real problems as all the oil will get squished out of the bearings...also the fueling won't have been increased sufficiently as the ECU isn't expecting it = running lean - very bad.
The point at which you get higher boost in the rev range progressively decrease up the gears as the loading on the engine is less (generally, i could get into the boost map based on throttle position, rpm and engine loading but i don't think its relevant at the moment .....I would get a normal recirc valve on there and check all your pipes. Be careful as B18FT_lover says, the plastic pipes on the solenoid snap as soon as you look at them!)

POE · Post by **POE** » Thu May 21, 2009 9:41 pm

yes there is the fact also that it is me looking into it too much ,it does seem to be in the higher rev range in say 2nd gear ,ive double checked that the dumpvalve isnt stuck shut,all seems ok,wouldnt it also cut out if there was a boost problem?i kept the boost into the red and it didnt cut?

chris1roll · Post by **chris1roll** » Thu May 21, 2009 9:45 pm

With the Richmod the ignition cut has been moved to a higher value. It has been set at a level below which you shouldn't melt your engine! Uphil in third in my old car I was running right off the scale, but touch the end of the red in 1st and you would hit the cut.
I can't give any explanation as to how he did it - micro electronics are not my best point - my DIY turbo timer went fizzle pop as soon as i turned it on.....

chris1roll · Post by **chris1roll** » Thu May 21, 2009 9:48 pm

Just a thought, may also be worth checking the pipe going into the MAP sensor in the ECU too...esp. since you'll have disturbed it to fit the modded ECU.