High Blms and light knock issue, advice? q_q

K

Koshe

Member
Joined
May 12, 2013
Hey guys,

Been having some issues come and go, and come back. The wife decided to give me my balls back so I'm now trying to make a small list of parts that will/might fix these reoccurring issues.

First thing, at WOT I'm getting knock. It's never gone higher then 3.0 degrees and sometimes I don't even get any but it's still something in the back of my head that makes me scared to go WOT in my GN.

Another thing is that my Blms keep coming back up to 142. I've done quite a few things to try and fix this but no matter what I do, they always come back to 142.

I also more than occasionally get a hesitation at the initial point when I give the car gas. Mainly noticeable at stop lights.

The cars starts up fine most of the time but occasionally its a little lazy. My idle likes to yo-yo around 400-800 rpms.

A little about the my GN... It's mainly stock and all original. I put in an AFPR to monitor my FP and that's it. Original 28 lbs injectors, my maf sensor looks like one of the rebuilt ones we can get at any autoparts store, vacuum lines are all new, hotwire kit, and it has a TT chip for a stock setup.

I've got a few great friends who live close by and are on this forum that have been giving me advice as far as what might be the culprits behind my problems but I wanted to run it buy more people before buying $2k in parts.

On Friday David and I are going to drop my fuel tank and check out the pump to see if its in good shape. Other then that do you guys have any advice?

Thanks in advance,
Koshe
 
Oh I forgot to mention that my ignition module, coil pack, spark plugs, and spark plug wires are all brand new... maybe 500 miles on them at most.

Fuel pressure is set to about 50psi only to try and fix the Blms/idle problem. Worked for a little bit.
 
If you are going to drop the tank just buy Racetronix fuel pump and sender and be done with it. Don't mess around with that old fuel pump. This is what I bought:
http://www.racetronix.biz/itemdesc.asp?ic=FPS-G7RXP340M&eq=&Tp=

Also reman'ed MAF's are a crap shoot. You could do 2 things;1-preferably buy Translator or 2 tap MAF and if you notice ANY difference in idle, it is no good.
Brand new does not equal good regarding electronic components for our cars. (MAF, coil pack, module)

And FP seems a little high. Most people say BLM's at 128 +/-10 are normal. Higher BLM's mean ECM is adding fuel possible vacuum leak. HTH.

Do you have a Scanmaster?
 
That's the same unit David was telling me to get. I figure I would at least take a look first just in case. But if the pump looks old then I will definitely get that racetronix pump assembly. I bought the car about 6 months ago and I haven't had the chance to see what pump the previous owner had put in, I do however have a ScanMaster. :)

I've checked for vacuum leaks on multiple occasions but since I don't have a fog machine or anything fancy I just ended up replacing all the lines and made sure all the hose connections were tight. I do need to make another inspection though. Ft. Bragg roads are harsh, maybe something has come loose.

Lastly, is there a difference between the 3.5" LS1 MAF and 3" LT1 MAF, other then their diameters?
 
Just keep in mind you have 2 issues; idle jumping stumbling and possibly BLM's. They may not be related. Take care of the pump situation first. There are a lot of vacuum connections in back of the climate control too. I am in the process of replacing my 9 port vacuum connection there. You can do a search on the LS1/LT1 MAFs. I really don't know the difference but I think I have the LT1 one. Love it. 255 at WOT is a beautiful thing. I had issues with stock MAFs, including one that didn't code, and the Translator is THE way to go.
Do you have a boost gauge?
Do you have a fuel pressure gauge?
 
I installed a fuel pressure gauge on the fuel rail but I'm still rockin the digital boost gauge :( lol
 
In regards to your high BLM's, if you've already replaced all the vacuum lines and checked the usual areas for leaks as well as checked for cracks in the driver side header, try putting in a new PCV valve.

When I had a smoking problem on my car one of the things I did was change the PCV. It didn't stop the smoking one bit but my BLM's dropped 5-6 numbers :) Do a search. There are others who found relief from high BLM's just from changing the PCV. And if it doesn't work you're only out a few bucks. I used this one http://www.nos4gn.com/servlet/the-820/buick-grand-national-parts/Detailbut others have had luck with other brands.
 
You could have a vacuum leak at the egr valve and/or at the throttle body shaft seals. I would search craigs list for a used smoke machine or do a search here or on google for boost pressure tester. Or take it to your mechanic and let him use his smoke machine. As for the fuel pump, you could either get a mechanical gauge on a long hose and place it under your wiper so you can monitor it, or get an electric gauge (About $200) and place it in your dash somewhere so you can always monitor it. Enjoy those new balls!
 
Lol, thanks GnRick

and 626Gn, I do actually need to buy a new PCV valve. It was part of the original plans but somehow got lost in the sauce.
 
Bescurred said:
50 psi is to high for your fuel pressure...pull the vac line off and set it at 42
Click to expand...


For mostly stock - you got that right.
I was wanting to scream it from the first post.

For leaks - just either make or buy a cheap boost tester.
You can find all your leaks that way - easy breasy.
And now that you got your balls back - it will only cost you 25 bucks - tops.

If you really think you need to isolate the HVAC vacuum lines - just unplug and cap the (SUPPLY) one on the firewall check valve T.


X10 on the PCV's
Those are almost as bad a crapshoot as the MAFs.

EGR?
Not sure about NC inspections on 25 yr old cars - even though my mom lives there
But in GA - I rip it off!
And the vacuum crap that goes with it.
Add a EGR delete plate.
Done.
 
GNICETRY said:
Just keep in mind you have 2 issues; idle jumping stumbling and possibly BLM's. They may not be related. Take care of the pump situation first. There are a lot of vacuum connections in back of the climate control too. I am in the process of replacing my 9 port vacuum connection there. You can do a search on the LS1/LT1 MAFs. I really don't know the difference but I think I have the LT1 one. Love it. 255 at WOT is a beautiful thing. I had issues with stock MAFs, including one that didn't code, and the Translator is THE way to go.
Do you have a boost gauge?
Do you have a fuel pressure gauge?
Click to expand...


Tap on the stock POS MAF when it is idling.

Does it stumble and bumble when you do?
If it does - you have found your criminal.
 
Koshe said:
That's the same unit David was telling me to get. I figure I would at least take a look first just in case. But if the pump looks old then I will definitely get that racetronix pump assembly. I bought the car about 6 months ago and I haven't had the chance to see what pump the previous owner had put in, I do however have a ScanMaster. :)

I've checked for vacuum leaks on multiple occasions but since I don't have a fog machine or anything fancy I just ended up replacing all the lines and made sure all the hose connections were tight. I do need to make another inspection though. Ft. Bragg roads are harsh, maybe something has come loose.

Lastly, is there a difference between the 3.5" LS1 MAF and 3" LT1 MAF, other then their diameters?
Click to expand...


Assuming the car is still more or less stock - I would think a modern upgraded FP of any type, with a hotwire kit - should be in order - ASAP.

If you can't spring for the Racetronix unit - find someone selling a Walbro 255 - they are plentiful and cheap.
That would at least get you solid.
Add the hotwire kit while you're in the neighborhood.

That addresses one of the main issues.
WOT blast are fun - but not so much with a crappy, 25 year old FP.

And oh - a fuel filter while you're at it.

Speaking of which - you didn't say the state of the car - but a general spring cleaning may be in order.
Take a peek at your Turbo outlet hose and make sure you aren't drizzling any oil.
 
I love Breaking Bad... ooooh that's TIGHT TIGHT TIGHT. :D

Ok, so when I bought my GN, it had all original parts, and was in very good condition.

I've done pretty much the entire spring cleaning except for the diff fluid, and PCV if that was on it; I cant remember. I have some Royal Purple Diff Fluid which I'm going to put in sometime next week when I get the chance.

Fuel Filter is practically new, maybe 500 miles on it at most.

As far as the EGR, I'm almost positive that with the 5.7 TurboTweak chip it's not even being used.

Last the current fuel pressure. I know 50psi is high and I cry every time I pop my hood :( but when I try to lower it to the recommended 42psi line-off the idle get so bad; it almost seems like the car is going to stall.

Now based on what you guys have been telling me here I've already put in a few orders. I went ahead and ordered the Racetronix 340 pump with full assembly, 60lbs injectors w/ new 5.7TT chip to match, and LS1 MAF sensor + translator.

David and I pulled the FPump and and the thing had cobwebs growing on it.

I'm still looking for a good PCV Valve, is there any other reputable places to get one other then from Highway Stars for a stock set up?
 
Koshe said:
I love Breaking Bad... ooooh that's TIGHT TIGHT TIGHT. :D

As far as the EGR, I'm almost positive that with the 5.7 TurboTweak chip it's not even being used.

Correct - on the part about not being used with modern chip sets.

Of course - it, and it's associated plumbing is still lurking.
Hence - X2 - my recommendation to rip it off.
Unless of course - you have to pass a visual emmissions inspection.

So if you don't have to pass emissions visual - and it is not being used - why let it reside rent free?
Click to expand...
 
either way - it leaks bad under boost. But they all do.[/quote said:
Agree. The best thing to do is test it before you leave the store. At least that way you can leave with the best of the bunch.
Click to expand...
 
Lol Heisenberg, I really don't have a good reason as to why I haven't removed it. I'll get around to it soon though. Still need to clean my engine bay quite a bit. Its filthy in there(Please don't judge me, lol).

So the PCV1162 doesn't fit our cars based of the Autozone web page. But on that thread 626Gn linked up top they said just to use some extra hose for the install.

You guys just mentioned getting the all metal PCV but the only one I could find that was all metal on the Autozone web page was the PCV1126. :confused:
 
Sorry, was not aware the 1162 is no longer available...Is buying the correct one from any one of our vendors not an option?
 
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