Today is the first day that I've driven my Blazer since doing my conversion. I took it to the muffler shop first which was about a 2 mile drive with open headers . It didn't seem like it was running real well but there was alot going on.

On the way home (now that it was quieter) it was time to see how it was really running . I quick stab of the pedal and the engine responded quite nicely, but when I let off to level out it surged like it was running out of gas. Well I've driven it about 10 miles now and it seems to "surge" when the vacuum gauge is around 0 or when it's making the transition from boost to vacuum. I also had to make a try at a full throttle blast and it wouldn't rev how it should've, it would start to rev and then cut out like it was starving for fuel and then try and get going again only to repeat. I let off the 3rd time it tried this.

This made me think that I had a vacuum leak, so now that it was quieter I gave it a once over listening everywhere. On the passenger side all the way towards the back of the manifold I can hear like what sounds like a vacuum leak. The only thing that I can think of that would be leaking back there would be the intake manifold gasket. I felt all around back there with my hand and couldn't seem to locate it. Since I'm new to the Radix I'm wondering if that sound is normal back there, like the air making the turn in the J-tube or something. Vacuum on the gauge is 17 at idle so I'm wondering if it would be this high if I had a leak. What is the best way to find a leak?

Something else I've noticed while it has been ideling in the garage is it sounds like it might have a slight miss as well.

If I pull it off tomorrow to try and find the leak do I need new intake manifold gaskets, if so where do I get them from?

Thanks,

Bill

 

There are 2 vacuum ports on the back of the manifold. Make sure they are either used or capped off.

Who tuned it?

Stock cam? I have a slightly larger than stock cam and I still see 20 on the vacuum gauge at idle.
EDIT: I see the GT2-3 now. I think you should get better than 17 with that cam. It doesn't have any overlap. Does the brake booster modify your vacuum line at all?

Make sure the manifold is tq to specs. It’s not very tight.
New gaskets should have come with your kit, right? If not you either need F body gaskets (8 grey individual) or the type in the plastic housing. They are red and each set of 4 is held together by the plastic.

What pulley are you running?
Injector size?
Inline fuel pump?
Fuel pressure gauge?

 

return fuel system or non return? either way check your fuel pressure and report back.

you might want to check and make sure you did not damage the intake gaskets, been known to happen (even to me) from time to time.

Depending on the manifold, you may need one of two style gaskets...take some pics and post them up.

 

Do you have a SES light hooked up? I'd scan it and check for codes...make sure all of the injectors are plugged in. If it misses too much it will go into reduced power mode...you really need to log it or at least monitor it with a scan tool

Dave

 

Thanks for the quick replies.

The motor is an 05 LQ4 and the kit I ordered is supposed to fit it. That being said I have all of the parts installed that came with it, including the fuel pump, injectors, gaskets and the stock 3.2 pulley.

I had Speartech tune the computer when he did the wire harness for my truck. Magna wanted me to send my computer in to have the tune installed but I'm hoping once my tuning software arrives I can get them to email me a tune since they still owe me one.

The first thing I thought of was that maybe I didn't torque the intake bolts correctly but I went back and checked them and they were tight (89 inch lbs). I installed the kit with the motor on the floor so one would "think" it would've been hard for me to screw up the gaskets, but I'm not ruling that out .

I have the returnless fuel system but between the tank and the fuel rail I'm running a corvette regulator/fuel filter. My fuel pressure stays steady @ 59 psi and doesn't seem to be changing when I'm having the surging problem.

I do have a SES light hooked up and it is on. It's been on since I started the Blazer and I was thinking that it was because of the lack of exhaust. I ordered EFI Live last week and am hoping to see it arrive the first part of this week. But until then I can't do any scanning to see what's going on inside.

Here are the pics of the intake, not sure if you can see much or not, if there is something specific you need to see let me know and I'll take a pic of it. I've also got one pic of the original gasket that was on the factory intake.

[IMG][/IMG]
[IMG][/IMG]
[IMG][/IMG]

 

Are you running closed loop or open? If you ran open headers for awhile you might have screwed your LTFT's and the motor could be running incredibly rich. When I first did my 6.0 swap I increased the fuel tables hardcore to be safe and when I first started monitoring my wideband so I could tune it I was running below 9.9 AFR, and it would surge like you are talking about. Also, if your IAT's are really high the computer might be pulling a ton of timing, which could also cause surging. When my I/C pump went out I was seeing IAT's as high as 217* at high-RPM WOT, and it surged like that too because I was running like -8* of timing or something ridiculous like that.

 

... I KNOW you will get that figured out and on the road soon enough...

... new school in old school retrofit is bitchin... that K/5 is gonna scream

 

I got my hands on the tuning software and the wideband yesterday but now I'm confused more than ever. I don't even know how to tell if I'm running in open loop or closed loop.

I started playing with the EFI live scanning software yesterday but I don't know what to scan. I did figure out how to read the SES code and the code it was showing was P0102 so I cleared it and it didn't seem to make a difference. In fact it comes on after I start the car almost everytime. If I clear it and drive it stays off until I restart.

I also have the LTFT PID turned on but I'm not seeing a change at all when I'm driving they just stay at 0.0%.

After much reading I decided I should install the WB which is a LM1. I did the calibration and installed it and at cold idle it showed 11.8 pretty steady. I went for a drive and I saw it go as low as 9.6. Now here is another confusing part, under heavy throttle it actually raises, I saw it over 15. It's raining here so I can't really do a wide open blast but from all of my reading all of this sounds like it's acting just the opposite of what it should be. When I came back I let it idle and it read a steady 12.4. I know what your thinking and it's problably what I thought which is the meter is bad. When I pulled the stock o2 sensor it was black and it's only been in there for less than 50 miles so I must be running rich like the meter shows.

All of this being said if someone can point me in the right direction I would be very appreciative.

Thanks,

Bill

 

Just a continuation of the last post, I pulled one of the plugs and it is covered in black.[IMG][/IMG]

 

Do a free air cal on the wide band O2. Pull it out of the bung after the truck has been off for awhile. Let it hang in the air. Push the button 3X to get it into calibration mode then 1 more time to actually calibrate it. Mine was reading perfect at idle and then would read really rich when I got on it. http://media.putfile.com/100-1408

After the free air cal it was right on and I didnt change anything in the tune.