69cutlass

Hello, new to the board and hoping for some advice. I've done a TBI conversion on my 87 Monte Carlo and am having some issues. It runs rich but no black smoke and runs a bit rough. At times it hunts a bit and surges once in a while. Can't seem to get to run at the base timing of 0deg and have to set it around 15~20 advance, and yes I timed it with the ESC connector off. I have attached what Winaldl data I could get thus far. Unfortunately my laptop battery is no good so I have to plug it in to use it which means testing at idle for now.

Vehicle info: TBI from 89 5.7l GMC truck.
- "No egr hooked up"
- New GM crate 350 (290hp version)
- Stock TBI Intake off 89 GMC 5.7l truck
- New fuel pump, fuel pressure steady at 11psi all the time.
- New injectors, FPR, and all sensors.

I tried everything I can think of and suggestions I've found reading through posts here and the web but nothing seems to help. 4 different ECMs (7747). We are stumped. Computer is stock for 89 5.7L. Stock except EGR setup removed.

For a time we thought we had the wrong damper but apparently the 6.1" diameter is the one GM lists for my application along with the timing pointer they gave us.

I'm not sure how to read every value in the winaldl data, anyone have any thoughts and info on the winaldl data that stands out as bad and what may cause it?

Cheers,
Chris

RFmaster

Cutlass

I have taken a look at your data log and your engine configuration. The problem is with your new GM 350/290HP engine. The problem lies in camshaft selection that GM has chosen for this engine - quoting from 12499529 data sheet:
"The 350/290 HP engine uses an aggressive flat tappet camshaft to achieve the level of performance for its intended usage. Camshaft lift is .450” intake / .460” exhaust. Camshaft duration (@.050”) is 222 degrees intake and exhaust. Lobe centerline is 114 degrees. Normal engine manifold vacuum for the 350/290 HP engine is 10-12” Hg at idle (650-750 rpm)."

Stock TBI ECM (1227747) that you have with a stock EPROM calibration was tailored to a milder camshaft (LO5 used in vin K 87-95 trucks called for I/E 0.382" / 0.402" lift I/E duration @.050 165.9/174.8 deg, LSA 111.9 deg). These engines idle at 600 RPM and 18" of vacuum all day long and would be done by 4000 RPM!

With 222 deg of overlap exhaust gas reversion is a serious problem at low engine RPM. Exhaust reversion is when exhaust gases are momentarily flowing backwards, during the valve overlap phase of the camshaft at low RPM's (idle). As a result exhaust gases end up in the intake manifold causing EGR like effect at idle. This is why this engine has rough like idle quality, but this also drives MAP and o2 sensor nuts! ECM relies on these sensors to deliver correct amount of fuel.

All is not lost, but to get that engine play 'nice' with ECM will require custom tune to get around cam overlap.


//RF

The problem i

69cutlass

Thank you so much for replying. This is actually my buddies 87 MC that I helped put the TBI on. I did my 69 cutlass without any issues. He was in charge of buying a new motor for the MC that he liked. My fault for not checking better what he bought! I assumed at 290hp it wouldn't be an issue.

Unfortunetly I don't have a chip burner for this. Can you recommend someone that could do a custom chip for me by looking at the data logs???? Is that www.tbichip.com any good??

Thanks!!

RFmaster

Well, tbichips.com is one route that you may take. Since your friend has engine specs Brian at tbichips.com can come up with a reasonable tune. Make sure that you provide him with a complete list - ECM, engine, trany, rear end ratio, exhaust, TB size, injectors, Fuel Pressure, etc.

He may get tune very close the first time out - 350/290HP are popular and he may have done it before. So, if you chose to go that route prepare information list and talk to him in detail. Be ready to do several back and fourth before you get tune close enough.

//RF

69cutlass

Anythign else you could recommend?

Also, is there a good websites or docs you know of onthe web etc that I can learn and read up on all the stuff winaldl displays and there meaning?

Cheers,

Chris.

RFmaster

I have to admit that I am partial to DIY tuning so I'll have to recuse myself from further recommendations. There is a lot more to it and learning curve will take time. Here are couple of links that should give you general over view of what is involved in DIY tuning.

https://www.thirdgen.org/forums/tbi/...bi-theory.html

https://www.thirdgen.org/forums/diy-...ns-needed.html

//RF

69cutlass

Thanks again.


Can I ask one more favour? Here is the winaldl data log from my 69 cutlass, I was wondering what you thought of the info and what needs addressing?

Cheers,

Chris.

RFmaster

I'll take a look....

RFmaster

VSS=0 so if it is there I am assuming that car is parked.

Looks like you have code 43 set (see last column of you data log) - verify by shorting pins A&B of ALDL connector and observe SES light blinking. This may explain why BLM's are nearly constant (operating in open loop INT=128) and O2 is not swinging between 200 and 800 mV and is nearly constant around around 500 mV +/- 100.

Idle MAP values are nice = 36 KPA is about 16 to 18 in-Hg

Do you have a custom chip in your ECM???

Over all BLM's are around 128 +/- 3 counts so that VE tables are close.

//RF

69cutlass

Him well I just got the car out of storage and when I first data logged it it was running in closed loop and the O2 was cycling as it should. Then I played with the timing as I've been told that the Olds 350 likes a lot of advance with HEI and TBI, actually around 20deg if you can believe it. Now I believe at 15~18deg it ran better. I then set the idle lower as it had raised higher than I like. After this it doesn't seem to go into closed loop and the O2 stays constant, where it was cycling back and forth like it should before.

It's a stock chip, I'll have to get the prom ID next time I'm at the shop to make SURE it's a 1227747 for 5.7L. I do have a 1228747 stock ECM as well. Do you know what the difference between them is and can it be used in place of the 1227747 in this case?

I kind of quickly did this datalog before running out for the weekend. I'll have to re-tune and do a road test and see if I can get things back to closed loop when I get my laptop battery charged and working again.

Thanks again, I really appreciate the help and advice.

BTW, can you recommend a decent chip burner (not to pricey) that will accept these olders proms?

Cheers,

C.

RFmaster

1227747 was used on full suze 1500 & 2500 trucks and chevy vans from 1987 to about '92. It has Knock sensor (KS) and ESC module to retard timing when knock is detected ($42 mask). 1228747 ECM ($4F mask) was used on heavy duty trucks WITHOUT knock sensor (5.7 & 7.4L). Due to omitted KS timing calibration for 8747 ECM is very conservative when compared to 1227747 (ASDU). EPROMS can not be swapped between the two ECM's

2732A EPROM (UV) are for all practical purposes should be remanded to museums. In their place a FLASH memory chip and chip adapter (check MOATES) make chip burning process a snap. You still need EPROM programmer - there are several low cost units for less than $100. TunerPro-RT is tool of choice for data acquisition and bin file modifications. The lowest price chiptuner is you - overtime you'll know more about what your engine likes and dislikes - and be able to make changes very quickly.

//RF

69cutlass

what do you guys think, I've been told by a number of people with this GM crate engine (see above) to change out the cam for my buddy as tuning with a new chip will be lengthy and still won't run right in the end.

SO I've been recommended this cam for my buddies application. What do you guys think?

http://summitracing.com/parts/CCA-12-388-4/

Cheers,
Chris.