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Need help setting up my new tbi stroker?

camok5

camok5

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I just put in my blazer a new 383 stroker and need some help working out the bugs. So far I have put about 450 miles on it and have been having some issues. first let me give some engine specs; chevy 383 running a cfm-tech bored out small block tbi with big block injectors and a FPR set to around 16psi, custom chip from tbi chips and they also helped me pick the mild comp cam to go with my engine.

First problem: It idles fine untill it warms up then it starts surging.

Second problem: It will bog down around 2000rpm but runs great once it gets up around 3000 rpm.

Third problem: it just doesnt have as much power as I think it should but feels like there is more in it, it just needs to be tuned right.

Also I have hooked Winaldl to it and logged data but I cant figure out how to find it after I saved it or how to transfer it onto a disc to put on my house computer?
 
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I would say your FP is too high. If you had a chip made for yuor set up and you're using the BBS injectors having 16 psi is just drowning that poor engine with fuel. Try backing the FP off to about 12-13 psi.
 
I'll have to install winALDL again and see if I can figure out where the log goes. Hmm, looks like if you let winALDL install in the default locations, your logs might be in C, program files, winaldl Saved mine as a .txt, but open it with Excel instead.
 
I also think your FP is way to high. From the way you are describing the way it runs sounds very rich to me. I would go back the stock +-12 psi and work from there.
 
Could the engine running to rich also be causing the surge at idle?
 
Yes, as the ECM may get a little "lazy" in trying to control the injectors...the pulsewidth may need to be so small (idle, large injectors, high fuel pressure, low fuel demand) that the ECM/injectors simply can't work fast enough, and they dump more fuel than necessary. Datalog, see if you are indeed rich, then work with the fuel pressure, see if your lean surge goes away.

Reason it does it once warm is that the ECM is trying to control the AFR ratio when in closed loop, when it's cold (and runs good) it's running on preprogrammed values, whether that means rich or not.
 
bear in mind too that your narrow band o2 can't really tell you what's going on if the mixture is beyond a very narrow window. Presumeably you're not going to do your own tuning so you're data logging for Brian to burn you another chip? If you can afford it, get a Zeitronics ZT2 WB o2 controller and display or similar. These can read afr's from 10:1 to 20+:1 where as a NB (I believe ) can only read from 14.2 to 14.9?? someone correct me if I'm wrong on that, but it's a pretty small window.
Reading the WB will give you a much better idea of what's going on fuel wise.
To run that much fuel pressure you'd HAVE to change the base pulse settings which I doubt has been done. Surging can be slowed by reducing the reaction time the ecu uses to react to the o2 switching, but again, this wouldn't've been done on your chip.
 
Here is an attachment of my log data when I was running 16 psi FP. Can someone help me read this and possibly help me figure out why my truck is bogging and hesitating. I have since dropped my FP down to 12 psi and it didnt help but it does seem to be surging less. I will get more data of how its running now as soon as I have time.
View attachment 20070607_190706_LOG.txt
 
I'm not a pro at reading/deceiphering those, but there are some questions I've got based on that. (easier to read if you open it in excel BTW)

Why did your coolant temp never really move? Are those celsius, and if so, why is it so low? Wrong t-stat comes to mind if those are celsius numbers. About a 160* stat if that's the case.

Your knock count is 46. I'm assuming this log is after the vehicle has been run for a bit? How is your timing set? Have you ensured it's correct? If so, back it off a couple of degrees and see what happens. EFI is EXTREMELY picky about base timing, since all other timing calcs are based on that. A 2* difference can be night and day.

IIRC, winALDL with the '747 bumps the engine idle up to 1000RPM, and does something with timing (no knock retard or something along those lines) so it doesn't give you a total picture of whats going on timing-wise.
 
Are you logging BLM and Int numbers? They didn't show up if so. Those are the most important numbers to be able to figure out what adjustments need to be made on the fuel maps.
 
They are there, but opening it up as a .txt file the numbers are all shifted under the incorrect header. Excel will put the numbers in the right spot. He's running rich in quite a few cells, BUT if the O2 sensor isn't hot enough, those readings could certainly be off.
 
Thanks dyeager, if I would've looked a little closer I would have seen what I was looking for.:o
That bugger is way rich, the long term fuel trim (BLM) is down into the 90s should be as close to 128 as possible. Log it again with the fuel pressure set at 11-12 psi and send to whoever is doing your chip.
 
My timming is set to 0* and yes I'm running that cold. I put a high flow water pump and a high flow 180* T stat when I put the new engine in and boy did they work too well. I will be putting a regular 160* T stat back in eventually. Could that be causing any problems? The 02 sensor is a heated 3 wire so that shoudnt be a problem. Now that I have been running at 12 psi FP its working alot better but still has some hesitation problems. I will post another log data but I dont have excel, I can use open office if that will work better.
 
If you're not careful and go installing a cooler T-stat the engine won't allow the coolant temp sensor to do its job properly so the ecm will never go closed loop.
 
Here is the datalog from 12psi sorry I cant seem to figure out a better way to link it and I dont have ecxel plus open office wouldnt let me attach it. I think I was a little backwards in my thinking about running a 160 T stat and I believe I should put a 195* in instead. Someone tell me if I'm wrong but I think I need to get the engine to run hotter because it doesnt ever seem to warm up enough, even when sitting in traffic.
View attachment datalog12psi.txt
 
You running headers too?

In any case, put a 195* t-stat in there, see how it does. You aren't costing power with higher operating temps.

The O2 sensor has to get hot enough to work correctly, it's probably stumbling once it warms up because it *thinks* you are running rich due to the O2 sensor readings...I didn't add them up, but if you were closed loop, idling, your O2 sensor should be bouncing between high/low voltage, instead looks like it tends to stay high.

Look at the TPS vs. O2 voltage. When you increase the throttle (increases heat in the exhaust) you tend to go lean with the O2. Otherwise, with closed throttle, you *tend* to be staying rich.

Keeping the engine hotter MAY be just enough to get the O2 working correctly. This is why sometimes people need to run a heated O2 with headers...not always necessary, but often.

Replace the t-stat, see if it solves the problem. There are a few things in the ECM dependent on coolant temp, it's expecting/wanting 195* unless that was changed in the chip.
 
You have to be careful when looking at oxygen sensor voltage, in fact oxygen sensor voltage with a 747 is darn near worthless especially when datalogging because of the sloooow update rate. Instead look to make sure the sensor is working and not sluggish (this one appears to working ok) and then watch the long term (BLM) and short term (Int) fuel trims to see what needs attention. If the oxygen sensor is making close to 1 volt and fluctuating, or the cross counts are up then the sensor is working ok.

With the way the data looks I'd say you're still rich below 3 thousand RPM and real rich at an idle. Does the engine backfire through the intake when it stumbles? It may be lean in acceleration enrichment (AE) which is usually the case when aftermarket intake manifolds, better cylinder heads, bigger cam etc. are installed .This is easily adjusted when a new chip is burned, just make sure and tell whoever is burning your chips. Usually when there is too much AE the engine wants to load up and/or run sluggish, so I doubt this is the problem. I'm guessing the hesitation will get worse when the rest of the fuel map is leaned out unless the AE is richened up.

I would change the t-stat back to a 180 degree as well, the 160 is just keeping the oil temp low enough that it's loading up with fuel and moisture. I would highly recommend getting that oil changed as soon as you can, I'm sure it's saturated with fuel from your rich running problems.
 
That O2 sensor is switching, (sometimes) but having the majority of the points measured (yeah, the refresh is horrid on the 160 baud ECM's) STILL showing the engine to be rich, especially at idle (assuming the 1.2/1.7 TPS readings are essentially the same throttle position) either the O2 sensor is cold, the engine is really that rich from something else, or the O2 sensor isn't working right. Still somewhat guessing based on O2 voltage of course. Let's call it "averaging". :)

I think we all agree the t-stat is wrong, whether it's the culprit of this problem or not.

I wouldn't spend time with a 180 t-stat, especially if headers, that is not going to help your O2 sensor/fueling/closed loop. 195* is what it came with, run it.
 
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