'98 Eclipse Turbo FWD 4G63 Boost problems

[Emanuel]

I checked with FAQ and Search...

We've a 1998 Eclipse Turbo FWD with the 4G63-Engine and we cannot boost more than 0.9 Bar (13psi).
We tried to install a FuelCutDefenser to the ECU which should limit stock boost pressure sensors signal with the result, that the boost drops the more we adjust the FCD.
The Boostcontroller is an BLITZ SBC ID III, installations is faultless.
To me it looks like the ECU limits the boost-level. There's no fuelcut, just not possible to get more boost than 0.9 Bar (13psi).

Are there any known problems with the spring of the stock Wastegate-Actuator or similar?

Cheers, Emanuel

[LandoAWD]

Stock turbo and BOV?

List any mods please.

[Emanuel]

Thank you for your reply!



HKS Superdragger (cat back)
BLITZ SBC ID III Boostcontroller (connected directly between
Wastgate Actuator and compressorhousing nipple)
K&N filter pad
Stock BOV
Stock Turbocharger
Rest is bone stock.




Cheers, Emanuel

[LandoAWD]

My guess, and it is a good one, is that the little plastic 2g BOV in combination with the T25 are the problem. If you replace the 2g BOV with a 1g BOV, you will be able to hold higher boost, though the T25 runs out of breath around 16psi.

[Emanuel]

If I got you right the BOV is the problem?
You think it opens itself over a certain level of boost?
We tried to fully close the wastegate actuator as well, to get fuelcut @ one level to know what's up with the ECU.

I need to tell you that I've no idea about the 4G63, not the foggiest notion!
I know a lot about Toyota Turbo Engines and for me it "feels" like the ECU does not allow more than 13psi. It may comes from the Karman Fortek Airmass Sensor that the ECU does not allow more than a certain frequency. But it really can be that I'm completly wrong!

The stock charger is the T25 from Garrett? There's Kind of an Airrestrictor installed @ the entry of the compressor housing... I would understand when boost drops @ high revs but it should be possible to boost more than 0.9 Bar @ 3'000 1/min?

[LandoAWD]

THe BOV is notorious for leaking, and should be one of the first things to replace when modding a 2g.

As for the T25...you COULD run the thing up to 25psi, but it wouldn't have a long life. What I am saying is that the EFFICIENCY drops off after 15-16lbs. At that point, you are just blowing hot air out of it.

[spyderturbo007]

I had the same problem with my 97 GS-T but mine would spike to about 15psi and then drop almost immediately. I replaced the stock BOV with one off of a 1g and can easily run 18psi with no problems. According to GSXracer after about 15psi the T25 heats the intake air so much that there are no noticeable power gains. I would recommend replacing the stock BOV with one off of a 1g....then "crank her up!"

[spyderturbo007]

Oh...I forgot....do you still have the BCS installed (boost control solenoid). It's the little plastic "thingie" under the antifreeze overflow mounted to the frame with one 10mm bolt. It also has two small vacuum lines and one wiring harness attached. If you do you can do the following to remove the restrictor from the BCS....

"You can get a 1lb or 2 of free boost by removing the BCS restrictor (or waste gate solenoid as some people call it). First you have to move the coolant reservoir out of the way (you don't have to remove it from the car). Next locate the BCS restrictor I think it’s right next to the bracket that holds on the coolant reservoir. It is attached to the car with one 10mm bolt and has 2 small vacuum lines and one electrical line attached to it. It is probably only about 2" x 2" (I really can't remember it's been so long). Anyway, remove all of the lines and unbolt it from the car. If you look at the BCS you will see that the lower hole is smaller than the top hole. If you CAREFULLY (if not you are looking at about $60 for a new one ) use a drywall screw in the bottom hole the restrictor will separate from the housing. I just threaded the screw in a little and the restrictor started to turn. Then you can just pull it out. Then the good old "installation is the reverse of removal" (hehehe....I hate when people say that). Don't forget to reconnect the electrical (unless you only want 8 - 9lbs of boost)........Hint, Hint......The line with the metal clip goes on the bottom. Close your hood and enjoy your free boost. I did 2 cars right in a row and it only took about 15min with no problems. Just don't thread the drywall screw in too far and you will be fine. Have fun!!!

[95ClipseGS-T]

The 2g bov leaks at 12-13psi, plus the BCS should not even be hooked up anymore,My MBC eliminated the BCS all together.

[95GSTRaCeR]

yes 95ClipseGS-T is right, from looking at your pictures it looks like the bcs is still hooked up, when you run a boost controller you eliminate that. I would definately replace that bov before you try anything else, becuase it isnt going to hold anything over 13 psi.

[97_3clipse]

it your BOV man,this olter guy said ,it leaks after 13psi,theres is a whole thread called "BOV" about on the best ones.

[JoeWagon]

Check for boost leaks too. http://www.vfaq.com/mods/ICtester.html It's a good thing to do periodically also.

That car is crying for a 1g BOV and new intake pipe. Good luck.

[Import2nr99]

I would definitely blame the BOV for this problem. Upgrade to the 1g bov and crush it (in case you ever boost over 20 psi). directions for that can be found on vfaq.com. also look into uicp and a better intake. maybe the fipk and a dejon tool pipe. great combo. also you may want to hack your dump tube. but definitely replace the BOV and the the bcs should be removed too. both are very easy. I'd only boost up to about 15 psi.. maybe 16. after that you're not going to get any improvements. Good luck

[Emanuel]

for your reply!
We'll try with 3RD Forge-BOV. I'll let you know what the results'll be.

Cheers, Emanuel

[BoostedSpyder]

ummm hey dude...

even if the BOV leaked above 12 psi, there is probably more to it than that because you aren't able to break 13 psi. also by your mod list and the pics i was wondering what kind of boost gauge you are running? there is no sign of it in the engine bay where one would normaly tap the line and no sign of it in the mod list, so how do you even know what psi you are running?

also: GET AN INTAKE! trying to get massive suction from the stock airbox is a MAJOR limiter as to the attainable boost pressures. no matter how closed the wastegate is if you can't get the flow at the aribox over a certain Hz it ain't never gunna happen. it's like trying to suck thru a straw vice a paper towelk tube. i'm also 99% certain that you have not hacked the dump tube so do that as well.

you will for sure need a BOV at this point. get a 1g if $$ is a problem, if you got the dough look into the GReddy type-S or a HKS SSQV. this also means you need to look into Upper InterCooler Pipes. Dejon Tools makes killer ones at a great price and GReddy makes good ones too.

the ECU has nothing to do with your Electronic Boost Controller. and i truely hope you installed your EBC "faultless"