Overboost

[Blue4Ice 0]

I think I am getting overboost in gears 2 and 3 (and maybe 4+5 but havent had chance to test). In first the stock boost gauge reads around 0.6-0.7 but in 2+ gears I get a steady 0.9 which seems too high. What are the likely causes of the problem?

Also I have been using the search and read a number of posts about overboost and a few mentioned a trick to test the waste gate by removing the pipe from the boost solinoid. I didnt understand 100% from the other posts, but can someone explain how I do this?

Thanks

[fmxa 61]

Recommend you first reset the ECU and run freescan to get a good handle on whats going on, and don't put too much faith in the stock boost gauge as its not very accurate!

To test the wategate capsule you disconnect the electrical connector to the waste gate solenoid. This removes any ECU control over boost and what you see is just mechanically controlled boost - should hit about 0.5 to 0.6 BAR and not go above this.

I think I am getting overboost in gears 2 and 3 (and maybe 4+5 but havent had chance to test). In first the stock boost gauge reads around 0.6-0.7 but in 2+ gears I get a steady 0.9 which seems too high. What are the likely causes of the problem?

Also I have been using the search and read a number of posts about overboost and a few mentioned a trick to test the waste gate by removing the pipe from the boost solinoid. I didnt understand 100% from the other posts, but can someone explain how I do this?

Thanks 

<{POST_SNAPBACK}>

[pitstoppete 6]

As far as i read it:-

if dash gauge is ok calibration wise, (they vary it seems from freescan and mech. gauges) it might go round to 1.0 bar sometimes if all is well (and chip is std and boring). this is normal, not a fault, as far as I can ascertain. (woo hoo!, proper flames out the back)

should go to 0.65 on the gauge max. when warming up from cold start. when the ecu sees over 75-78 ish deg C at the coolant temp sender, u should get up to 0.85 bar, with the occasional bit to 1 bar as mentioned.

(cool running 74 deg coolant thermostat originally fitted to mine never got the water hot enough to trigger full boost. spotted it on the first test drive.

with solenoid disconnected, you should see should boost go to 0.65 to 0.7 bar. if not, adjust wastegate rod length to change setting. getting this spot on helps with the 2800-3000 rpm stumble problem it's said.

also check all the small vacuum and boost hoses coming off the engine to the sensors and valves. mine were in dire need of replacement/some clips that actually sealed the joint etc.

[Blue4Ice 0]

Cool I will go and test the wastegate capsule now. Is there anything in particular I should be looking for in freescan? Is the boost reading more accurate on Freescan than the stock gauge?

[pitstoppete 6]

god yeah. freescan takes the feed from the sensors/ecu.

remember not to cack yourself when the check engine light comes on when u disconnect the switch. i did.

on mine the boost is all spiky (needle flicks about a bit up to 0.7 bar max) with the solenoid valve disconnected. this is normal too im told.

the VSS (speed sensor) has something to do with boost too. if the car is all std. u might see the normal condition of boost backing off after about 5-10 secs. of full throttle. this is the inefficent turbo/chargecooler pump struggling etc.

[Blue4Ice 0]

god yeah. freescan takes the feed from the sensors/ecu.

remember not to cack yourself when the check engine light comes on when u disconnect the switch. i did.

on mine the boost is all spiky (needle flicks about a bit up to 0.7 bar max) with the solenoid valve disconnected. this is normal too im told.

the VSS (speed sensor) has something to do with boost too. if the car is all std. u might see the normal condition of boost backing off after about 5-10 secs. of full throttle. this is the inefficent turbo/chargecooler pump struggling etc.

<{POST_SNAPBACK}>

Pitstop your pretty muh describing what I have seen before whilst driving so perhaps mine is ok and I dont have to worry lol. Last night was really cold and the car was regularily sitting on 0.9 bar which started to panic me but the extra cold air probably had something to do with it as well as what you were saying above. Its still worth a quick test though

Thanks for the help

[Kato 0]

This guide might be helpful.

http://www.lotusespritworld.com/EMaintenance/BoostValve.html

[Dermot 0]

Comments here are almost all spot on. I must correct one thing.

The VSS (speed sensor) has NOTHING to do with boost control.

Dermot

[pitstoppete 6]

Comments here are almost all spot on.  I must correct one thing.

The VSS (speed sensor) has NOTHING to do with boost control.

Dermot

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yeah, cheers Dermot. knew that werent right somehow, wasnt sure.

ps, how long did your injectors take to come from the US? do u remember?

is two weeks a long wait since they were posted from Illinois?

[Dermot 0]

I take it they are coming from John at WC.

If he used just normal airmail, they may have gone into the Post Office International system for VAT and import duty recovery. That is what happened to mine.

The likes of UPS etc. seem to handle this a lot faster.

Dermot