Hi there..

Tried to check my vacuum between the fuelpressure regulator and the plenum yesterday.. I got 0 in vacuum there So i started to check it out... and unscrewed the plug on the plenum that is for the fuelpressure regulator and when I had i loose ITS CASTED SHUT and it looks like a stock cast..
WHY!?! this cant be good ? running at 44 PSI all the time nomather what load and throttle...

Got some info and pictures on this page , the correct vacuum results, fuelpressure results, ohm checked the injectors cold and warm, compressiontest, sparkplugwire ohm controll and more..
You will also find alot of TTS Datamaster logs on the page, link to that on the right side of the komptest page.: http://www.alandsbrodata.ymex.net/z28/rep/komptest/

I will show you guys the 2 pictures here, but you will find more info on the page linked to above..

Here is the plug for Fuelpressure regulator, stock one.


And here is where it sitting on the plenum


Stock fuelpressureregulator, and its a 305 TPI , 1989..

 

Should it be like this ? was there made plenums with casted plug like I have ? or is it a construciton error ?! really dont know what to do about it...
Really need an answer about this..

info about everything you will find herer : http://www.alandsbrodata.ymex.net/z28/rep/komptest/

 

That does look wierd... My plenum on my 91 350 TPI only has one hole.... So honestly I couldn't tell you.

 

The backone (the leftone, thats bigger) is for HVAC (aircondition)

 

My '87 definitely has vacuum at that port. I'd say it's a manufacturing error.

 

DEFINATELY a manfuacturing error. The TPI fuel pressure regulator compensates for manifold vacuum that is pulling on the tips of the injectors, effectively increasing their flow-rates at idle. The regulator reduces the pressure as manifold vacuum rises to compensate for this by keeping the pressure differential across the injector the same. With the plug casted shut, you are probably seeing very rich operation on the log at low rpm, low load, that corrects itself as the engine is placed under a heavy load, higher rpm. Take a small drill and knock the plug out. Your engine will love you, and respond with increased fuel economy and smoother low-end operation.

 

Well I will drill it out and try again. I will also make some logs and see whats happening, I will also check the pressure so its not getting dangerous low or high ... the strange thing is that the car has been running real good for 4 years before the injector gave up..All problems started last year... after that with the 24 lbs/hr injectors (Accel) problems occoured.. and Yes i changed the injector constant in the PROM/CHIP to...

I hope it will run better when I drill this hole... Having problems when I have a gear in like D or [D] and holding Brake at stoplight.. it tends to go down in rpm and sometimes it will backfire when i rew it up on idle... maybe you have checked all the latest logs ??

as said I hope it runs better with the new hole..

 

That could be a tuning issue, try the changes I wrote in the last message. (AE)

 

But the things is that its not always doing it...