Map sensor reading too high

[traviz06]

I'm helping a friend get his 91 z28 running with a ls1 ECU, 1bar SD OS. It has the coil pack conversion on his tpi motor. It idles and runs okay. I'm concerned with some backfiring through the exhaust.
Are you/lt1 map sensors comparable with ls1 map sensors? Offsets any different? At idle he's around 40-50kpa but at cruise with hardly any throttle he is at 80-90kpa.

I feel this is way too high. We tried a different map sensor with same results. Both are confirmed 1bar map sensors (039).

Any suggestions?

It's making it hard to know if it's running right . With wideband and be table tuning, the AFR is good but it's still running rough and backfiring randomly.

[Mrich0908]

I'm helping a friend get his 91 z28 running with a ls1 ECU, 1bar SD OS. It has the coil pack conversion on his tpi motor. It idles and runs okay. I'm concerned with some backfiring through the exhaust.
Are you/lt1 map sensors comparable with ls1 map sensors? Offsets any different? At idle he's around 40-50kpa but at cruise with hardly any throttle he is at 80-90kpa.

I feel this is way too high. We tried a different map sensor with same results. Both are confirmed 1bar map sensors (039).

Any suggestions?

It's making it hard to know if it's running right . With wideband and be table tuning, the AFR is good but it's still running rough and backfiring randomly.

Post a log file from the scaner and your editor file it helps others taht know more to help you better.
Different year map sensors have different values in under engine , airflow , general , map sensor linear / offset. So when you switch between different sensors you need to enter different values.
what spark table are you using with what ecm?

[traviz06]

Post a log file from the scaner and your editor file it helps others taht know more to help you better.
Different year map sensors have different values in under engine , airflow , general , map sensor linear / offset. So when you switch between different sensors you need to enter different values.
what spark table are you using with what ecm?

I will post a log shortly, laptop is charging.

We are using the stock 02 z06 spark table pasted over. about 20-24 degrees at cruise.

I was considering the offset as well, I cannot however locate any offset values for a tpi/lt1 map like he is using.

[Mrich0908]

I will post a log shortly, laptop is charging.

We are using the stock 02 z06 spark table pasted over. about 20-24 degrees at cruise.

I was considering the offset as well, I cannot however locate any offset values for a tpi/lt1 map like he is using.

You can not just use any ole spark table . Nothing about that ecm your using matches the sbc. What ecm are you using? 0411? The whole ecm has to be reconfigured. Start with a 99 fbody spark table. Start and modify from there. copy the high to the low.
Did you use the z06 ve table aslo?
What about injector data? Did you set cam retard properly?
There is allot of features that should be turned off at first so your not chasing your tail. So much I cant even remember off the top my head. Youtube is a great place to watch videos and learn.
Proper map and data is crucial though. What mods does he have?
He has three videos watch and follow along .
https://www.youtube.com/watch?v=PG4LKjib3Ug&t=36s

[Jay@HAP]

What kPa does your MAP show KOEO?

[traviz06]

THanks for the response guys. Like I said, I am helping a friend with his swap. he has an '02 vette pcm. We did a flash to a 1bar SD OS for f-body, so it will have f-body timing and VE table. I already tuned the AFR with his wideband so the afr is good while driving even if the MAP is reading wrong. Timing at cruise shows a relative low 20-24 degrees. Here is the tune though. Help me understand why the KPA reads so damn high. Thanks!

[Mrich0908]

Kpa looks normal to me.
Read this link, about 9 paragraphs from the botom talks about the tune. His injector data , spark tables , maf tables (if using one) ect all have to be changed. Your trying to run a motor that was never intended for this ecm. Thats why its running like poo. Use a fbody tune it will improve . BUT how did he set cam timing retard? Makes sure thats correct . The motor needs a tune.
http://www.gmtruckcentral.com/articles/24x.html

[traviz06]

He is using stock ls1 injectors, no maf. That's why we loaded SD 1bar os for f-body, not Vette sorry. It is a Vette ECU though.
I'll ask about the cam timing and get back to you

[RonSSnova]

I'm curious why you aren't using an LS1 map sensor?
Once you get the correct map sensor, and it's reading right, you will have to redo the VE tuning.

Is the car running closed or open loop? I'll assume open if you tuned the VE part throttle with the wideband.

That ecu was used in all sorts of vehicles as I'm sure you know.

Ron

[traviz06]

It's a tpi motor. No where to plug in a ls1 map.

I'm confused what is setting cam timing retard?

It is open loop and AFR is fine now. No maf sensor. 1bar SD OS loaded.
He said he checked timing and it's at 85 degrees? How's that possible. He swapped around the 1x cam sensor but it made no difference in how it ran, timing then shows 147 degrees.

He did a crank relearn, it made no improvement.

It does not appear odd that under low throttle/load while cruising that his kpa shows maxed sometimes?

[Mrich0908]

http://www.gmtruckcentral.com/articles/distributor.html
I dont have a lsx sensor either but had to change the values . His car wouldn't run at 85 degrees.

CMP offset = cam offset or cam retard offset pid. Its your cam sensor.

[RonSSnova]

For the map, two solutions.
Drill and tap the plenum for 1/8 npt, install hose fitting, then hose to LS map sensor. Get a pigtail to connect.

Or, put a mighty vac on the present map sensor, suck it down to 20 kpa, and note the reading in the scanner. Do the same at 100kpa. Then change the map sensor settings in the tune until you get it right.

What reluctor wheel does this setup use?

I've tuned lots of LS engines. I have never heard of cam timing retard

[Mrich0908]

For the map, two solutions.
Drill and tap the plenum for 1/8 npt, install hose fitting, then hose to LS map sensor. Get a pigtail to connect.

Or, put a mighty vac on the present map sensor, suck it down to 20 kpa, and note the reading in the scanner. Do the same at 100kpa. Then change the map sensor settings in the tune until you get it right.

What reluctor wheel does this setup use?

I've tuned lots of LS engines. I have never heard of cam timing retard

Its not a LS engine as he wrote . Its a gen 1 sbc tpi motor with 96+ vortec sensors to run a gen 3 ecm. The 96+ has a 4x 1x crank cam sensor. They sell 24x 1x crank cam sensors for the swap.
Thats why I keep telling him he has to have the whole motor tuned . I just went through this .

[traviz06]

Its not a LS engine as he wrote . Its a gen 1 sbc tpi motor with 96+ vortec sensors to run a gen 3 ecm. The 96+ has a 4x 1x crank cam sensor. They sell 24x 1x crank cam sensors for the swap.
Thats why I keep telling him he has to have the whole motor tuned . I just went through this .

I am not sure what you mean by having the 'whole motor tuned". It starts and idles fine. The AFR values are fine. There is just something we are missing with the timing and possibly the map sensor issue.


@RonSSnova, He has a 24x reluctor wheel.

[Mrich0908]

I told you why . Over and over. It starts and idles so why are you here then?
I can start a car with a Windex bottle spraying gas into the intake manifold and it will idle fine. How well do you think its going to run.That ecu is meant for a completely different engine with completely different heads cam injectors cylinder head ports compression ratio in/ex valves fuel pump sensors tq converter. Get the drift Its 99.9% different.
The 0411 swap is able to be done because the 5.7 came in vans from x year to x year. There is already a map calibration of it. You went coil over plug . There is no map for it.
Your "friend" has to tune his motor with a wideband. Or send it to a shop to get tuned. All of it. There isnt a magic table that fixes this problem.

[RonSSnova]

You could be a little nicer sir.
I believe traviz06 is attempting to help tune this.

Ron

[Mrich0908]

You could be a little nicer sir.
I believe traviz06 is attempting to help tune this.

Ron

I could. It would be nice to stop repeating my self.

[traviz06]

I could. It would be nice to stop repeating my self.

As I previously stated, It is tuned with a wideband. It does have a coil per plug conversion. It has a 24x crank wheel and a 1x cam wheel. it idles and runs at 14.7:1 afr. The only issue it has is a a stumble/backfire of sorts and the observation that the map sensor is reading way too high, maxed out even under the littlest of throttle. If I could get assistance in figuring out where in this timing issue the problem may lie, I can use it to assist my friend who is relying on my help and we will both be happy motorists.

[Fast4.7]

As I previously stated, It is tuned with a wideband. It does have a coil per plug conversion. It has a 24x crank wheel and a 1x cam wheel. it idles and runs at 14.7:1 afr. The only issue it has is a a stumble/backfire of sorts and the observation that the map sensor is reading way too high, maxed out even under the littlest of throttle. If I could get assistance in figuring out where in this timing issue the problem may lie, I can use it to assist my friend who is relying on my help and we will both be happy motorists.

Start with the Express van 5.7 Timing maps and go from there. The 5.7 maps have more timing in some areas than the LS stuff. Even my stock Express Van actually enjoyed a good bit more timing than the factory timing maps provide. With the LT4 Hotcam and Vortec heads, I idle at 30* of timing and run down the road in the 30-50* range depending on the RPM and Load. I am also running nearly full advance of 26* out of 32* max, at WOT by 2,600 rpm.

I really doubt the MAP sensor is giving a false reading. It only takes 15-20% throttle at lower rpms on a TPI or LT1 to cause MAP readings like you are seeing.

[traviz06]

Start with the Express van 5.7 Timing maps and go from there. The 5.7 maps have more timing in some areas than the LS stuff. Even my stock Express Van actually enjoyed a good bit more timing than the factory timing maps provide. With the LT4 Hotcam and Vortec heads, I idle at 30* of timing and run down the road in the 30-50* range depending on the RPM and Load. I am also running nearly full advance of 26* out of 32* max, at WOT by 2,600 rpm.

I really doubt the MAP sensor is giving a false reading. It only takes 15-20% throttle at lower rpms on a TPI or LT1 to cause MAP readings like you are seeing.

Thanks
I'll give the van tables a shot.

Would too *low* timing table cause all the backfiring issue we are having?