Over boost problem

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Over boost problem

Postby JPope » Thu 26.05.2016, 01:00

I have a Fed M100 that has just recently started over boosting bad, as in 3/4 to 1 bar. I have the stock exhaust, well most of it the axle back was rusted completely through when i got the car summer of 2014, i was going to fix it but then had to have the trans rebuilt, i have just u.der 2000 miles since i rebuilt the trans and now it is over boosting. I have checked the air hoses and every seems fine. I will also be trying to use some throttle body cleaner tonight to see if that can help narrow down the search. Thank in advance for your insight
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Re: Over boost problem

Postby lotusflasherman » Thu 26.05.2016, 01:28

Sounds like you need to look here ..forum.lotuselancentral.com/viewtopic.php?f=31&t=25147
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Re: Over boost problem

Postby lotusrepair » Thu 26.05.2016, 02:14

I went through what I thought was overboosting. Are you getting a check engine light on after it overboosts? The injectors should shut down if it is going over. I had a time when the gauge was going all the way and it turned out to be a bad wire connection on the transmitter. I Cleaned the terminals and the grounding point. It read correctly after that.

Chris
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Re: Over boost problem

Postby Brit-Car-Nut » Thu 26.05.2016, 02:53

Are you sure you are "overboosting" or is your gauge just misreading the boost pressure? If you overboost, the ECM will shove the car into limp mode which is like having the brakes slammed on. The check engine light will come on for a few seconds/minute and then the ECM will reset and the car will drive normally until you overboost again.

If you are ONLY seeing a high boost gauge reading, then the ground wire on the bracket for the inducer / sender is loose and you need to remove the screw, clean the metal bits, maybe replace the M5 Rawl Nut, and reassemble after coating the connections in dielectric grease.

Turbo-Boost-Transducer.jpg


Transducer-Mount.jpg


If you are really overboosting, then the first thing to check is that the wastegate is not stuck closed. Follow the link from lotusflasherman for insight in what to do if it needs to be freed up.
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Re: Over boost problem

Postby JPope » Thu 26.05.2016, 03:06

lotusrepair wrote:I went through what I thought was overboosting. Are you getting a check engine light on after it overboosts? The injectors should shut down if it is going over. I had a time when the gauge was going all the way and it turned out to be a bad wire connection on the transmitter. I Cleaned the terminals and the grounding point. It read correctly after that.
Yes when it goes to one bar i get a engine light and loss of power
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Re: Over boost problem

Postby JPope » Thu 26.05.2016, 03:08

I know the guage is right i have cleaned the wires and it goes to limp mode. And of course i have nothing flammable in the garage. Go figure.
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Re: Over boost problem

Postby HJ2 » Thu 26.05.2016, 08:14

:roll:
If you always do what you always did, you always get what you always got
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