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If the switch(s) for the clutch or breke petals that works with the cruise control is not adjusted properly, then the cruise will not work. And if the ECU does not think the clutch is released or that the foot is not off the brakes, it may refuse to increase boost above base boost. So there is a common element to check out.
otherwise:
You need to find out if:
The turbo and ducting can create boost.
If the BPC is working ok.
If the BPV is working ok.
In a calm traffic environment, remove the hose from the wastegate actuator and then drive with a -gentle- throttle and see what boost you can get to. Not in first gear or you may just get wheel spin. The boost will go to around 40% thru the red then the ECU will stop triggering the fuel injectors. That is called a 'fuel cut'. It is a transient thing and does not create a cel or any other persistant state other than making you want more.
If you hear any engine knock, put the hose back.
Put that hose back!
If you get major boost, the BPV and turbo and intercooler (IC) and pipes and hoses are ok. The boost pressure control soenoid valve (BPC) has probably failed, this happens. These are not cheap. You could install a MBC to get boost, get a new or used BPC. It is rare for the BPC to not be working because of an ECU or wiring issue. But you can check for signs of mice eating wires etc. If you can borrow a BPC, try that and if you get boost, you need one that works (or a MBC).
If you get some or same-old low boost, then figure out why. Ispect the IC for damage with the grill out. There will be some bendt fins and stone damage. No problem, we are looking for holes. Check the hoses to and from the IC, and the coupling hose up towards the throttle body. Try tighening clamps to see if any are loose. Also check the two ~1" hoses for the idle air control valve (IAC) at the thottle body (TB).
The bypass valve (BPV) is black plastic over by the battery and connect to a 1" hose or pipe that returns air to the intake between the air filter and the turbo. It has a small VAC line from it to the throttle body. Boost pressure goes from the TB thru this to the BPV to help keep it shut. If that does not happen the BPV leaks. That hose on a 95ET will be turning to dust if the original. If busted, cracked or split, replace it. If hose was bad, after replacement, test run for boost.
If still no boost, the BPV might be bad. Remove the return hose. Feel inside, the BPV should be open at idle from the manifold vacuum. If not it probably has a failed diaphragm and will need to be replaced. You can remove the VAC line and the valve will close... don't get your finger pinched!
Might be good to inspect the air cleaner if all else fails.
The turbo might also reduce boost if the spark plugs are the wrong ones etc.
In situatuions like this, it is extremely rare for the turbo to be at fault.
posted by 65.68.10...
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