3 of my 8 injectors are junk so I'm going to order some Bosch III's this week. I guess I'm just wondering beings I have the plenum and runners off to do the injectors should I be considering replacing the egr valve and fuel pressure regulator? I would rather not spend any more money than I have to at the time, but I really don't feel like ripping it apart again next year to replace another faulty part. I'm still learning on these damn things and don't wanna make a rookie mistake, but I don't want to go overboard either. Thanks guys.

 

I did the Bosch 3s..I figured while I had the plenum off, I would add the adjustible fuel regulator and the blockoff plate for the egr, since it was removed from the programming. I also changed the Mat sensor since it is under there and I was seeing 90* temperature when the garage was only 60*. I also changed the IAC since it was so nasty it looked original.

Well now I have a slight hard start problem with a hunting idle at startup..and I don't know where to begin because I changed so many darn parts.
Moral of the story: Change whats broken. Not much else.

 

Unlike the multitech injectors, the fuel pressure regulator is not a common failure item and neither is the MAT sensor. Unless it's physically damaged the sensor rarely fails. Rather than throw money at these items that are likely fine, I would suggest spending $200-$300 on a used OBDI scan tool so that you can view data stream and verify that all is as it should be.

BTW, It is typical for the MAT to read higher than ambient air temp. It is installed in the rear of the plenum in order to read actual plenum air temp because the plenum on stock engines tends to run very hot and affects actual inlet air temp. If the engine is modified with high flow intake parts, low temp thermostat, functional hood vents and cold air or ram air intake, it lowers the plenum temp and helps correct this problem.

 

Had my Bosch III installed a couple months ago...
If fuel regulator is fine, keep it... read plenty of people breaking diaphrams / leaking fuel onto engine (yikes!), etc....

My neighbor with an 89 TPI said that mine idles so smooth (EBL P4 helps too)

Rafael

 

Get a gasket set for the intake. If your gaskets are old, they will probably come apart when you take the runners off. You won't get a good seal if you try to reuse/fix them which will cause air leaks. Engine won't run right because you'll be getting air after the MAF sensor.

 

My mat sensor reading was on a cold motor in the morning...otherwise I wouldn't have changed it...
You will be very happy with the new injectors... The idle is amazing...

 

Be cautious when you order the injectors as many of the Bosch III designs may be rated at higher fuel pressures. 28 lbs/hr injector on an LS1 engine is not 28 lbs/hr anymore at 43 psi

 

Thanks for the response guys. My injectors and intake gasket showed up Friday from Southbay. Very fast shipping and great customer service. I was kind of hoping you'd say if it's not broke don't fix it as I've heard of guys having problems with regulator diaphragms. I'll probably start tearing into it this week after work if all goes well. I just didn't want to tear the entire intake and runners apart and then have the regulator or egr valve go bad in a couple months knowing my luck. I've owned the car for 3 years now and I've only had one trouble free year with it which was last year. I'm thinking I'll know this thing like the back of my hand when it's all over with.

 

Just want to give a shout out to Southbay fuel injectors. I got my injectors in and the car back together yesterday and she runs like a top again. Great service, fast shipping and an excellent product. Thanks again.

 

EXCELLENT! Happy everything worked out well!