Just started tuning my new engine. I have about 50 miles on the engine. I have a few questions. I'm starting to understand more and more how to tune but there's a lot that I don't Know and now im stumped with a big problem. My current setup is a

Sbc 350 / .030 over
Fully balanced rotating assembly
edelbrock Rpm performer intake
Comp cam 262 computer controlled cam
190 cc pro comp heads.
Flat top aluminium 5cc pistons
9.8 compression
Edelbrock headers w/ 3'' exhaust
bbc tbi w/80lbs injectors
Aeromotive FPR set at 22psi with stock FPR block off. / stock regulator
255 lbs Fuel pump
Accel Header spark plugs.
EBL flash




Before i explain my current problem ill explain how the car ran before my problem came about. My car would accelerate good as long as I stayed under about 45 % throttle. I had popping out of the tbi if it was a sudden heavy acceleration or anything after about 3500 with 40-50 throttle.

On Wednesday I was on my way to school when I started my car to a clunking noise coming out of my cat. Now at this very instant, i noticed i could no longer rev my engine past 2000. Now obviously my cat had blown so I went to school and gutted my cat.

After shining a light down the cat to confirm my cat was clear. I started my car. Now the clunking noise stopped completley now that all the honeycomb was out of the cat but, The problem still persisted. My engine just wouldnt rev. :/

I still need to weld my muffler on so I'm wondering; would the lack of so much backpressure cause my engine to do this ?!

So my car is just BARLEY driveable. It barley did enough to get me home. It even stalls here and there. and any type of heavy acceleration makes my tbi pop.

So ive tried a few things to no avail. I really need some help.

I have a few ideas. A list of what i think i should try and some that ive tried.

Things I have tried:

1. I put my stock TBI FPR back on today and same problem.

2. I found 3 burned spark plug wires today that were to close to the headers. I replaced them and still the same problem.

Things I will be trying:

1. try replacing spark plugs? (Ive heard the accel header plugs aint the best)

2. maybe i dont have enough back pressure or something is still clogged up in my exhaust? (I did run it with the long tail pipe disconnected from the cat. Same problem. So i was gonna disconnect the Ypipe also and see what happens)

3. replace distributor or coil?

4. Bad fuel pump? (before I took my aeromotive off i squeezed my return line after the reg. and my pressure went up from 22psi to about 60psi)

5.Bad injectors?

6. A hole in one of my pistons :/ (Imma run a compression test soon...)

The thing that gets me is this all happened at the very instant that my cat went bad.

Now im at home sick and rain is going to be keeping me from doing much troubleshooting for a few days.

Thanks alot guys. I hope I can get a few suggestions.

 

did you do any datalogging before the motor started acting up? the only thing i cant think of is you changed something, if your TBI is popping that sounds like a backfire, meaning the explosion that normally takes place in your cylinder....is doing it in the intake

if youve got a datalog post it up and ill try to help

 

I just found one. This datalog was on Wednesday before I had gone to school.

Now I really dont think that I had changed something. I remember that after I was done tuning that same day, my sister had come home from her university and wanted to hear the way my car sounded, so I went to go start it up for her and reved a lil then turned it back off. I reved it up to about 3500k.

When It was time for school at 6pm that same day, thats when i started my car to the clunking coming out of the cat.

Ok, so here is me tuning on Wednesday before all of this happened:

http://www.mediafire.com/?pmj8ivvw7qgf9q8

Here is what the car drives like now(This was yesterday, you can see how many times it stalled on me):

http://www.mediafire.com/?tsu4kd8488z6nex

I also had my uncle check it out and he said it seemed like it was running out of gas which is when I did the test for the fuel pump and the pressure rose to 60psi.

Now, we came to see this because when the car starts to die out, the injectors die out with it, which would seem sort of normal to me, although I never noticed whether the injectors quit before the car dies. Made me wonder if the injectors could be bad or my fuel filter clogged.

 

3500 isn't bad, not really enough to cause any damage under normal conditions, that's my shift point usually, my only concern wikth your fujel thoery is the clunk, id do a compression test and make sure your cylinders are fine, is it a consistent clunk? Can you replicate the problem during a log and highlight it some how?

 

No, i dont think that last time I had reved my engine had anything to do with it.

That last rev might have just been the last straw that my cat. converter was going to take before it blew.

The clunking is completely gone, it went away after i had gutted the cat on Wednesday, the clunking was due to all the honeycomb that broke in the cat.

My car seems to idle fine although sometimes it will just die out all of a sudden.

I guess im going to start with a few simple things first, such as spark plugs, fuel filter, disconnecting the y pipe, and im thinking of swapping on my old injectors.

I'm scared about the compression test :/ but ill be running one of those as well.

 

Go back through your base settings, they need to be different for the new engine.
Likely needs at least a 350 bin & more timing.

Start by getting it warmed up in the driveway, do VE learns & log it.

You will want to monitor fuel pressure while running & driving to check on the fuel pump.
Check plugs.
If there is any strange noise under a valve cover pull it off for inspection.
Also vacuum test for valves & timing.

Let us know as you get some testing done.

 

If your cat is gutted pulling your y pipe off isn't going to make a difference, you'll just be a lot louder, consume more fuel and maybe see a slight increase in torque, but its also illegal in most states, if there's no clunk and it was the cat just move on, I've got edelbrock headers running to a 3 inch y pipe, with 3 inch all the way back, backpressure isn't an issue, cats are meant to flow, when they break they restrict airflow that's all.

I say do your compression test, take your findings, tune it to a 350 as mentioned above and give it a shot, keep in mind when you tune for a 350 you might need to adjust timing as well its late and I can't remember off the top of my head what the numbers are, also if its just dying randomly, change the fuel filter like you planned, and run some seafoam in the tank, it will clean up your tank, lines, and injectors, before you spend money on new ones, I've never had tbi injectors fail on me or anyone I know, just give em a good cleaning first and go from there, my tbi likes to die randomly too, no warning or sign just dead, fires right back up tho, also check on your tbi's regulator while you're at it, if you havenjt already

Happy hunting

 

Ok so heres how everything is going. I did a compression test on 5 of my cylinders, 1,3,5,7, and 2. They all tested out at 150-160psi.

I replaced my spark plugs, fuel filter, ignition coil, distributor cap, and rotor.

So i tried starting her up and at first, engine didnt want to start, it would start for about 2-3 seconds and die, so i held the gas and it finally started up. I let go, the engine stayed idling. I waited about a minute, then I gave it gas and it reved! I reved it the way up to about 4000. So i got pretty happy, I let her warm up.

I tried to go for a drive... It started doing the exact same thing... It may have improved a tiny bit, but for the most part it still isnt going past 1500 while driving and about 2500 while idling. Every here and there it actually revs up a bit more than average for a slight second (maybe 3000rpms), this mostly happens once its been idling for a good 5-10 seconds without any throttle.

So i set the car and park and went to observe my injectors. I notice that when i hit the gas pretty hard, they shoot strong and then they look like they start dieing out. Looks like fuel problems ?

So after some research and a few suggestions from friends here are my next ideas:

1. May have dirty injectors- going to swap in originals
2. My brand new fuel pump has gone bad- Plan on doing a volume test
3. May have a bad O2 sensor- Will replace.
4. IAC valve bad?
5. Im lost ...

I will be installing my new msd distributor tomorrow as well my msd coil that just came in the mail. Its sort of frustrating, but i know ill get it sooner or later.

Hope I can get some more help. thanks every1

 

Do a fuel pressure test, when you say it dies out do you mean likeon the last part of the rev as it drops rpms they start spitting? Like on of on off realy fast?

 

When i had my aeromotive on I was using the high pressure spring that ranges from 20-40psi. I had it set to 22psi for the tune and the injectors.

With the regulator on, my pressure would stay constantly at 22 when at idle but when I would WOT, the pressure would drop quite a bit, not to 0 but pretty close. But i believe it would do the same when the car was still running ok.

Ill put my regulator back on since i found out that wasn't the problem. I dont know how much the pressure should drop when you hit the gas. but ill observe how much and when it drops and when i rev it.

I think i know what your getting to, I know when the injectors are running out of gas they make that spitting on and off type of squirting. Its not doing that, the stream is actually just sort of widening back up a bit when the car starts to loose the rev. Like the injectors are dropping voltage or something. This is what made me think it could have been a bad O2 since it sorta feels like its being controlled by the computer...

Also when im in the car watching my RPM's trying to rev it, The revs dont just stop at 2000, they seem to bounce up and down, like from 1000 to 2000 and then back down and back up, not always exactly 2000 but always somewhere around that range.

 

Injectors don't really run off orf voltage, the stream is produced byn the ecm telling it on, of,on,off etc just 1's and 0's

 

I think i might have found the problem, either a clogged fuel pump or bad fuel pump.

I disconnected my fuel line to do a volume test, i cranked the engine for about 10 seconds then went to look at how much gas went into my lil test tank. There was almost no gas at all, So i pulled my fuel line back up to watch the line while I turned the key to prime the fuel pump. I primed it about 3 times untill finally a tiny weak lil stream of gas started to flow out.

I dont think the stream is supposed to be this small, I belive my pump is clogged because it seem to be priming ok, pretty loud but they've always been loud.

Its to bad Ill have to be siphoning the tank again and bringing the tank down again. I think im going to buy another tank as well, and flushing it.

Thanks 4 all the help.

 

Where did you tap for the volume test? If it was at the tank id say ok to the pump, if it was after your fuel filter id replace that before you drop your tank and spend money on a new pump, when's the last time you changed your fuel filter?

 

I replaced the fuel filter on friday.

Ok, so i brought the tank down, I tested my pump in a bucket of gas to see if it would give me the same results. This time it shot a pretty good stream of gas when i had a friend prime the pump with the key. So the pump seemed to be working OK. Although the lil filter at the bottom of the pump was pretty dirty.

While my lines were disconnected I shot my gas lines through with my air compressor.

I tried to start the car with my pump inside my gas bucket and my lines hooked up, It started and I was able to rev my engine, I reved it up to 6000 and let go. Although I noticed I still had a surge.

This is what it was doing: Say I would hold the pedal in one position to bring my car to 3000, after about 3 seconds (With the pedal in the same position) it would start surging and drop back down to about 2000, Then if I put the pedal down some more the rpms would jump up again, and if I held the pedal there, they would then start to surge again and drop back down. Sometimes the rpms would stay for a while and sometimes they would drop

Ok so far at this point all I did was blow my lines through with my air compressor and I removed the fuel pump filter.

So I though, maybe the fuel pump is still not working to its fullest. Ill take it off and do a volume test.

When I took off the pump I looked down into the small rubber hose that connects the pump output nozzle to the metal fuel line. There was a small piece of metal right in the middle of the hose. I took the hose off and took out the piece with a screw driver. It was the metal nozzle lip fitting that clips around the edge of the end of output nozzle.

I think this lil thing was pivoting inside the hose and maybe causing the surge.

Anyways im going to test the fuel pump and if it tests out good then Ill put the pump back in.

Im almost sure the small metal ring was the problem along with the dirty pump filter.

Ill let ya know when I test the pump and put it back in.
Thanks!