After, finally get the LT1 up and running I have encountered yet another problem.

The problem is as follows...

When the car is idling and I hit the gas, throttle response is very slow.
When I hit the gas hard the car backfires like crazy.
If I drop the car into reverse it wants to stall and sometimes does cut off.

At first I thought this problem was due to me not having the rest of the exhaust after the y-pipe installed. However, after taking it to the exhaust shop and having my exhaust welded up and is still persistent.

New Parts
Optispark
MSD 6AL
MSD 8.5mm Wires
NKG Plugs
LS1 MAF
EGR is blocked off.

The computer was reprogrammed to delete VATS, EGR, and set shifts points.

I'm guessing the the timing could be off alittle. How should I have the vacuum lines attached? Which vacuum lines did you guys keep? I'm not running AC.

By the way I installed some polyurthene motor mounts and besides the normal vibration the engine does seem to be a little jumpy. (Sometimes it seems as if it wants to jump out the car) So I guess it could be sensing a false knock.

If you guys have any ideas or suggestions please feel free. I would really like to get this car running correctly. Its killing me that I have really not had a chance to drive it in about two months.

Thanks,
Jay

 

is the computer programmed to account for the different MAF? try unplugging the MAF and then starting the car.

 

Unless you have it reprogrammed for the LS1 MAF, then the MAF readings and calculations are going to be way off. I don't know if anyone else has actually ever used the LS1/7 MAF and made it functional.

You can not physically adjust the timing on the stock optispark. I think the ACCELL or MSD aftermarket optisparks do allow for it but its not necessary.

Got a ALDL cable you can hook up to the PCM? Then get a program like tts datamaster(trial version) and see whats going on with the sensors. You can even record a session then upload it on here for others to look at.

 

I don't see how it would run with an LS1 MAF either. I hate to be a wet blanket, but have you done a compression test?

 

i would have to agree with the other guys rg ls1 maf is probabley the issue. what did ya do toget it running????

 

I had the computer reprogrammed by madz28 to account for the LS1 MAF sensor. I will try to unplug and see if that affects the performance.

I have not done a compression test yet either. What should I look for when doing this test?

I don't have an ALDL cable that I can hook up. Where can I get one from?

The main reason I got an LS1 MAF sensor is because it only costed my $75.

If you guys have anymore suggestions I would greatly appreciate it.

Thanks,
Jay

 

if you unplug the MAF, then start the car, it will run in whats called Limp Home Mode, where it switches to speed density. if it runs fine like that, you'll know its the maf. sounds very similar to when one of my maf wires broke a while back. ran like absolute crap.

 

Compression test the cylinders to make sure they are within 15% of each other. Should be over 125psi as well.
I hope its the MAF, but once again last weekend I got caught blaming the electronics when it was something much more basic. Car drove great, but idled terrible and stalled when put in gear. Bad rings in #3.
Are you actually in Detroit proper? I'd like to see your swap.

 

Guys,

I unplugged the MAF and the idle was very smooth along with the throttle response being improved, but once I dropped it into gear the stalling and hesitation occured. After, I put it back in gear and cut it off then try to restart it. The car is very hard to start...

I'm going to go and buy a compression tester today and see if I that checks out okay.

Furthermore, do you guys think a could have a bad batch of gas or would that affect the idle and startup also?

This is what I had done to my computer by MADz28
-Performance/Power tuning (premium octane use w/LS1 MAF)
-Knock retard desensitizing
-Disabled Speed Limiter
-Disabled VATS
-Disabled EGR
-Disabled AIR
-Disabled CCP codes
-Disabled A/C codes
-Increased Shift Firmness
-Rev Limiter set at 6000 RPM

Which gas should I use? I know premium but some gas stations have 87, 89, 91, 93, 94.

Sean,

I had a few wiring issues along with starter and battery problems. My biggest hassle was the VATS. It would allow me to start it sometimes and sometimes the security light would just blink.

ACCLR8N,

I'm on the west side of Detroit. If you would like to come out and see it let me know. Just give me a time and day.

Thanks for all the help,
Jay

 

Guys,

When reving the engine and just when the car is idling I hear the exhaust popping and backfiring like crazy. Especially when the car gets warm.

I'm starting to believe that my passenger side motor mount is causing the knock sensor to pick up a false knock. The car is shaking violently.

How are those metal tabs on the passenger side supposed to sit?

Thanks,
Jay

 

Have you checked fuel pressure, checked fuel pressure regulator, and checked for leaky injectors?

Use at least 91 octane since you got for a performance tune from madz28.com.

Double-check your spark plug wires, backfire and not wanting to start could happen by having the plug wires installed wrong.

 

Okay as the title says, I crossed two plug wires. However, I still have a problem.

After switching the crossed plugs the car no longer:
1. Backfires or pops like crazy.
2. The idle and throttle response are smoother.
3. The car does not shake and hesitate either.

However these problems are still present.
1. After putting the car in gear it stalls and sometimes will cut off.
2. After it cuts off it is very hard to start back up.

These problems are very noticeable when the MAF is plugged in. When I unplugged the MAF the problems are still present but they are not as bad as when the MAF is plugged in.

Beside that I do have an exhaust leak from the passenger side header that I plan on fixing when I get my new headers bolts and gaskets.

I also plan on doing a compression test and fuel pressure test to make sure those check out fine.

If you guys can think of anything I would appreciate it very much.

Thanks,
Jay

 

Check fuel pressure regulator by pulling off the vacuum line to it, if there is gas in that line or a really strong scent of gas then the fuel pressure regulator is probably bad. Even if its questionable, it wouldn't be a bad idea to replace it.

Check for leaky injectors by taking the fuel rails off of the intake manifold, so that you see the entire injectors. Prime the fuel pump by turning the key "on" but don't try to start the car. If you see a lot fuel come out of any injector, then you have a leaky injector. A fuel pressure gauge would verify this, the pressure would drop very quickly after priming the pump if there was leaky injectors or a leak somewhere.

What NGK plugs do you have in? Probably should have the NGK TR55's.

Is the oil normal? Normal amount on dipstick?

Both O2's are installed, right?

Could be dealing with a bad sensor too, but check out compression and what I mentioned above in this post first.

 

Are you getting any kind of codes? I just finished my install a while back and had simular trouble and had a code 15 I believe coolant temp signal. Believe it or not I never changed that because I was working on my idle and miss problem and after 10 weeks later I decided to change this sensor because it was on my list of thinks to do and wala the car now runs great. So if you have a code no mater how far it is from your problem, it may be the problem.

 

Where do I start...

When I got under my car today, I found out that my O2 Sensor on the driver was loose. It was loose to the point where it could probably have fallen out. So I tighten that up and retorqued the 02 Sensor on the passenger side. After that I seen a little bit of antifreeze on my oil filter only to look up and see that my freeze plug is starting to leak. After letting the car down I started to do the things Firebat suggested. First I checked the fuel press. reg. by pulling on the vacuum line where I smelled a good bit of gas. Could have been coming from somewhere else but I pretty sure it was the regulator. Next, I took off the fuel rail and turned the ignition key to the on position fuel came out of the number #1 injector, #3 injector and the #8. The first injector squirted fuel from it and the others were minimal.

Before doing what Firebat suggested I did start the car and see if the 02 Sensor being completey in affected the performance and it did. The car seemed to idle a little better. Furthermore, after dropping it into get the stalling started again. After turning it off once more it was hard to start again.

Now for my questions...

Should I buy some new injectors or have them sent to Cruzin Performance to see what he can do with them? If I do get new injectors would it be okay for me to upgrade to 30#/hr?

Which fuel pressure regulator do you guys recommend? I was looking at one from aeromotive for the LT1 that is on-rail type.

As for the freeze plug, how much work are they to replace?

Firebat,

I have the NGK TR55's and the oil appears to be normal. Thanks for the help.

Evo,

I still have to hook my service engine soon light up. However, my temp sensor is kinda of messed up. The part where you place the connector broke off and right now the connector is just sitting on the metals prongs that were enclosed by the part that broke off.

Once again thanks for all the help,
Jay

 

I think on camaroz28.com's classifieds, I've seen used LT1 injectors not sell for too much. It might be worth checking out.

I don't think it would be worth it to send in stock injectors to be rebuilt for anyone but thats all my opinion, I haven't researched that, but if you had some expensive aftermarket injectors that it would make more sense to me.

If you upgrade to 30 lb injectors, you will need the pcm reprogrammed, otherwise it should be ok. You won't see any gains unless you have aftermarket heads/cam or something like that if you upgrade injectors.

Do not get an aftermarket fuel regulator, the LT1 pcm adjusts for the changes. The higher pressure the regulator will put out will eventually be canceled by the LT1 pcm's calculations. I replaced mine with a borg-warner(stock replacement) one from O'Reillys.

 

Try double checking your xhaust at the y-pipe and at the o2 connections especially if you had to weld a bung on. I found a leak on the pass. side o2 bung using seafoam. My car ran like crap for ages until I sealed that leak. I know another notorious leak at the intake maniofold has caused similar problems in other lt1 motors. I know that I was able to hunt down alot of problems using Datamaster software and keeping it simple.

 

Are stock LT1 injectors 24# or 26#?

Firebat,

Since I will be replacing my injectors, I will probably go with something new just so I have the comfort of knowing that. With that being said, what are my options? Who has the best injectors available? I have made up my mind that I will remain stock for the sake of getting the computer reprogrammed.

As far as the regulator goes, how much did you pay for yours? The only reason I'm looking to get Aeromotive fuel pressure regulator is so I can add a fuel pressure guage.

Has anyone ever had to deal with a freeze plug leaking? If so, how much work is it to replace?
Thanks,
Jay

 

Stock LT1 injectors are rated at 24# at 43.5 PSI.

A replacement fuel reg should run around $30-$60. Aeromotive should be more expensive.

Head over to camaroz28.com's message board and do some searching on injectors and the LT1 freeze plug. I did a little searching but there is just a lot of information on LT1 injectors.

From what i've read over there, The FORD SVO 24#, which are supposed to be way better are rated at 39psi, so at 43.5 psi they are actually bigger than the GM 24# injectors. These injectors seem really good but i'm not sure if you would need a reprogram, the FORD SVO injectors are only 1.6% bigger. The stock setup is 24.9 lbs/hr to be exact.

edit: The Pcm will adjust for the slightly bigger Ford 24# injectors. http://web.camaross.com/forums/showt...ight=injectors

 

Stock 26# Accel injector set is $260 from Summit and you'd have them by Monday or Tuesday. Much better than what you got. The other end of the spectrum would be a matched set from TPIS for $400.

Even no-name regulators from the auto part store is going to be at least $60.

Pick one end of the freeze plug and tap it in with a large punch until it tips enough you can pull it out with channel locks. Clean the bore in the block, some sealer on new plug and tap it in. Re-fill coolant. Never did one while it was still in car though. I'm guessing it will be a pain to get square swing at it.

Edit: Accel lists 24# for 93 LT1s only and 26# for later. I've heard good reviews on the Ford SVO injectors as well.

 

Thanks to the help of ACCLR8N,

Today, I was finally able to do a compression, fuel pressure, vaccuum and a scan test.

Compression checked out good with an average of 194psi.
Fuel Pressure checked out between 40-43 psi.
The vacuum test also checked out fine.
The scan test results show no trouble codes.

Also today we were able to swap out my LS1 MAF with ACCLR8N's LT1 MAF and also use his fuel rail, regulator and injectors. Before replacing the MAF the car would run rough and will not start after letting it run for awhile. When we replaced the MAF the car not only idled better but it did not stall when it was dropped into gear and it started quickly after turning the key over.

After performing these test and swapping out the parts. ACCLR8N and I came to the conclusion that I should replace my LS1 with an LT1 MAF and probably get my computer reprogrammed once more to account for a stock LT1 MAF.

Thanks for all help,
Jay

 

glad that u figured out what it was.

 

Thanks...

 

Swapped out the MAF Sensor with Granatelli's MAF.
Changed the injectors now using Accel 26lb/hr.
Also changed the regulator now using Aeromotive Adjustable Fuel Pres.

The car started on the first try...

Then when right back to hard starting after I turned it off.

So I guess now my only choice to go ahead and the get the computer reprogrammed, which I was trying to avoid.

Jay