moneyman380

Let me start with what I have. 91z28 355 superram with heads cam and headers.

Car has been down for awhile now. Problem is it only starts when you give it quite a bit of gas and doesn't start easily. I posted this in the tpi forum but haven't got anywhere with it so far.

Here's what I've done
Swapped tps
Swapped ecms
Redownloaded bin to my ostrich
Tried stock eeprom
Checked sensor input on my laptop. (Tps iac and map)
Checked timing
Reset iac several times
Checked fuel pressure. At about 37psi. A little low but the pump was changed less than a year ago

I'm out of ideas. I even bought a smoke machine and checked for leaks Any ideas ?

bigal55

iTrader: (1)

How's your fuel pressure regulator? Pinch off the return line from the regulator back to the tank, what's your fuel pressure now? Does the engine start with starting fluid then continue to run without giving it throttle? Your low fuel pressure reading indicates either a restriction in the pressure side or possibly an "open" return (pressure regulator not restricting flow back to tank). The third possibility (not so easy to check) is a ruptured pulsator (little fuel line between the fuel pump and the hard line inside the tank). Low pressure / volume will cause your symptoms. Get back with the requested info. GL!

moneyman380

I ran the fuel pump with the engine off and was getting 43psi then when I pinched off the return it went up over 60psi. I don't have a pulsater in the tank. It was removed when the last fuel pump was installed. I'll try to start it with starter fluid Monday.

bigal55

iTrader: (1)

I read your other thread on this problem and don't see anything mentioned about your CTS. While data logging, what is the CTS reading? If the engine starts easily with a small squirt of starting fluid, you may need to increase your cranking fueling. Once the engine warms up, does the ECM go into closed loop? Does it idle once warm? What's the minimum RPM needed to keep the engine running? Can you post a log from cold start to warmed up so the tuning gurus can analyze it? Try to hold the engine at the lowest idle to keep it running.

Tuned Performance

iTrader: (92)

With a cold start datalog it would be hard to see if the engine needs more enrichment. The nb o2 doesn't become real active until warmed upto 5-600f.
The int is locked at 128 so without a wb o2 it would be hard to see if it's too lean on cold startups. If the engine starts better with slight propane enrichment and or starting fluid when cold sounds like enrichment is needed for cold start. I don't believe you mentioned if warm restarts are ok.does sounds like the camshaft change is the culprit .

moneyman380

I'll try to post some data log info tonight. Just tried to start it with starter fluid and it cranked right up with no pedeling. Then I tried to start it when warm and it wouldn't without me giving it some throttle. Atempted to move it but it just didn't have any power and kept on stalling out under load.

Tuned Performance

iTrader: (92)

Just look at your int at idle closed loop sounds like it's above 128.
If that's the cause due to the cam you might want to change the target idle speed alittle then work on ve in the effected areas 40-50 kpa area whatever area your engine idles vacuum ranges.
I wouldn't nesseceraly change cold start enrichment until closed loop idle is dialed in if the engine needs more fueling.

moneyman380

I did a datalog file on tunerproRT but it wont let me upload How can I share it ?

Tuned Performance

iTrader: (92)

Zip the attachment or rename the .xdl file as a .zip and attach it in the advanced option of posting. The paper clip icon will allow you to attach your file.
You might want to attach your.bin as well are you still running 22#hr injectors ?

moneyman380

heres my bin

moneyman380

Here is my data log short but it shows how I have to throttle the car to start and its hard to still. Also dies when I put it into gear. Oh I'm currently running 26lb injectors

Tuned Performance

iTrader: (92)

I had issues and couldn't change the .zip into a xdl . The .bin had the injector flow set to 24#hr so I changes it to #26 and added some fuel to the lower ve table. I hope this helps but it may need more work. feel free to send me a pm for my email address to send a closed loop idle. I think its running lean but it would be good to see your int in closed loop at idle.

moneyman380

Ok did another data log finally. Been busy with work but hopefully someone can help me out. I will post a log file

moneyman380

heres a log

moneyman380

Here is a real zip upload

Tuned Performance

iTrader: (92)

looks real lean like you need larger injectors/ higher fuel pressure. not sure your engine specs.

moneyman380

I rechecked fuel pressure and checked for an exhaust leak before the o2 sensor. There is one after it at my collector but I don't think that should matter. Here is another datalog, its short though

moneyman380

I'm thinking about pulling the superram off and re gasketing the entire intake to eliminate the possibility of a vacuume leak. While I have it apart I can swap in some 36lb injectors I have sitting even though the 26lb ones in it used to run it fine. Also can swap out the IAC with an new one and maybe even the fuel pressure regulator while I can get to it. What do you guys think?

Tuned Performance

iTrader: (92)

Since this development is new. I would fix the exhaust leak first then look for vacuum leaks.
If the tunes haven't made a difference on how it runs I'm thinking the exhaust leak maybe messing with the o2 reading. Is this hard start warm only or warm and cold start ?

Tuned Performance

iTrader: (92)

If the fueling increases have helped going from 43.5 to 50 psi your 26#hr will flow about 28#he. The 36s will work but you will need to start with stock ve settings then maybe lower them down to reduce fueling. For the cat to glow I would guess the ecm is overcompensating for the lean condition and dumping way to much fuel .

moneyman380

fuel pressure is sitting at about 43 psi and seems to float around under load. Will also drop down to low 30s under load. At this point I'm thinking the fuel pressure regulator could be bad. It would float around sometimes during this test even with the vacumme line disconnected. As far as the exhaust goes I'm kinda screwed on fixing. Its a slip joint at the header collector, but I do have plans in the future to have a shop weld flanges in place down the road. My fuel Air ratio gauge says its running lean off the heated o2. It seems to start hard warm or cold

moneyman380

Finished putting everything back together and still has same issues. Redid the superram gaskets from head to throttle body. Any suggestions Vaccumm leaks are out of the question and also for safe measure replaced my IAC since I had to remove the throttle body.

moneyman380

Any other ideas ?

GeneralDisorder

iTrader: (1)

If it needs lots of throttle then it's starving for air or actuating the throttle is putting it in flood clear mode, shutting the injectors off. Check if the injectors are firing when you perform this startup procedure with a noid light.

GD

moneyman380

Well its been awhile since ive had time to workon her , but I went ahead and checked the injectors with a noid light. All were firing when trying to crank over the engine. At this point I'm considering changing the fuel filter and all the gas in the tank to some fresh premium. Any other ideas ?

moneyman380

Here is a short datalog from today . Itsjust me starting the car cold and then letting it stall then trying to restart

moneyman380

I drained the gas and refilled with some premium and still doesn' want to stay running by itself. Also had to give it some gas to start.

Tuned Performance

iTrader: (92)

I forgot is this a new problem or did it just happen out of no where ?
You might need a Wideband gauge to verify that it might be running extremely rich. Then work on cold start enrichment.

moneyman380

I upgraded the headers and went with 1.6 ratio Roller rockers. But besides that it just sat.