5 to 7 lbs max boost!?

[DCEPTCN]

I bought my 2nd 87 GN a short while back and am just now getting down to addressing it's needs. One problem I was having was that the turbo (obviously quite old) wasn't spooling up very quickly and was maxing out at 5 lbs. of boost. I got a new turbo and put it in. (It took Napa 6 days to get me the manifold flange gasket!) After much checking that all points are good and tight, and screwing with the new wastegate, I took the car for a spin....it spooled immediately-great fun!- all the way up to 7 lbs. and that is where it stays. WTF I cannot- for the life of me- figure out what this damn thing needs to reach regular max boost levels. If anyone has been through this or has any suggestions it would be immensely appreciated.

 

[salvageV6]

Do you have an adjustable wastegate actuator?

Do you have an intercooler hose leak or uppipe leaky hose?

I was once perfectly limited to 15 psi. by a leaky hose. Rock solid boost too.

Unfortunately I was looking for 23 psi. at the time.

 

[DCEPTCN]

Originally posted by salvageV6
Do you have an adjustable wastegate actuator?

Do you have an intercooler hose leak or uppipe leaky hose?

I was once perfectly limited to 15 psi. by a leaky hose. Rock solid boost too.

Unfortunately I was looking for 23 psi. at the time.

Yes, got the wastegate opened up really well. ( I gotta remember to turn that back down when I get this problem solved!) I did not really think that the uppipe could affect it this badly....huh..but that has been checked and the couplers are brand new. I'm a 'worst case scenario' kind of guy, so I'm dreading that my problem will turn out to be a big pain in my a$$ manifold-related problem. I'm just hoping that someone will have that magic idea that makes this problem go away.

 

[Slow91z]

Check the routing of the wastegate Vac. hoses... got to http://gnttype.org/ ...you can find all the trouble shooting you need if you look hard enough.

 

[DCEPTCN]

Will do, thanks!

 

[DCEPTCN]

Originally posted by pdq4av6
Since you are having the same problem with the new turbo installed and the fact that
you just purchased the car, before you bought the car and was test driving it did the
boost ever go past 6psi? and do you have aftermarket gauges,boost,fuel press,knock,
scanmaster or other types.

I have to admit that, when buying the car, I was just so happy that the wife let me get it and that it was so cheap! Also, when test driving, I didn't check the boost levels,as I was having so much fun just 'seat of the pants-ing 'it (it had been a couple of years since I'd driven one). No aftermarket boost guage, as it is not necessary quite yet and the stock works fine- although, I do have an alky kit just waiting to be installed...as soon as this junk is straightened out.

 

[RareT]

Originally posted by DCEPTCN
No aftermarket boost guage, as it is not necessary quite yet and the stock works fine.

Bingo............ there is your problem. Just because the factory gauge "moves", doesn't mean it is accurate.

**Magic idea**......put a good boost gauge on it.

 

[DCEPTCN]

Originally posted by RareT
Bingo............ there is your problem. Just because the factory gauge "moves", doesn't mean it is accurate.

**Magic idea**......put a good boost gauge on it.

This, of course, is an eventual priority of mine, but even if one were to assume that the stock guage was completely useless-having owned a couple of 87 GNs, I know that 5 to 7 pounds is at least pretty close. I'm familiar with the pull of 12, 13 ,14 lbs. and this car currently pulls about half of that. ....just the same, yes- I need to pick one of those up in a week or two.