84 cross fire running rich at idle

Hello from central Florida
I have an 84 vette with cross fire injection.
has been running super richich since I got it .
this is what i have done so far ,
hogged out intake, installed a summit cam(largest with out changing converter, lumpy at idle)
Long tube headers, x pipe and resonators tp tone it down a bit.

replaced temp sender, Map sensor, TPS sensor, new 02 sensor, upgraded ECM from stock to a 8746.
So, the Question is should I just adjust VE tables in tuner pro or should I start with adjusting A/F at idle?????
I have Motes ostrich 2.0 Tuner Pro RT ( Latest) . I have not done any data Logging yet due to interior work being done to car.

Welcome to the forum.

First thing, if you haven't done it, is to balance the TB's and make sure the TPS is sending the correct voltage it idle. Confirm fuel pressure is in range as well. With new cam and other changes you most likely need tuning but there's no point if the basics aren't correct.

Well, its been a while, Life rules but I am back at the 84 crossfire, I did have to change ECM to 1227747 , still having Idle issues (really rich) starts out with low idle the as it warms up the rpm increase to 1200 and that is where it stays , fuel pressure is @13psi, replaced injectors and reinstalled stock intake. I have not done any data logging yet because it runs so poorly. I have tried different bins all have basically the same result.
has any one successfully upgraded ECM on the 84 Crossfire injection?? I know no one likes them

Are you setup to reprogram the 1227747 PROM chip?

dave w

Yes, using motes F&B and adaptor installed in 1227747

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Originally Posted by Gator

Yes, using motes F&B and adaptor installed in 1227747

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A data log can provide useful information, even when the engine is running poorly.
Base Pulse Width (BPW) is an important parameter.

dave w

Attachment 17354

Attachment 17355

Thanks Dave, I did need to Change BPW to 120, I will get some logging done and post the results

Quote:

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Originally Posted by Gator

Thanks Dave, I did need to Change BPW to 120, I will get some logging done and post the results

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My 1227747 tuning experience has shown me to keep the BPW "window" to +/- 10% of the stock setting. Typically the 1227747 5.7 Liter TBI has BPW of 135, so a window of +/- 10% is a BPW between 121.5 ~ 148.5. TBI Injectors have a BPW "sweet spot", to much BPW causes idle quality and low speed driving issues and not enough BPW causes hesitation and driving issues at upper RPM's.

dave w

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has any one successfully upgraded ECM on the 84 Crossfire injection?? I know no one likes them

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I started with an 83 5.0 F car auto trans ecm and calibration, then switched to an 84 5.0 F car ecm, then switched to a 1227747, and currently run a 1227427.

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fuel pressure is @13psi

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Changing fuel pressure always made a large difference when I was using a stock ecm. Generally I kept pressure around 10 psi back then.

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starts out with low idle the as it warms up the rpm increase to 1200 and that is where it stays

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Have you balanced the throttle bodies yet?

Thanks 1project2many, I am curious about the difference between 1227747 & 1227427?
The fuel pressure @13 has not been changed at least since I have owned it
as far as balancing throttle bodies, do you mean the IAC's or mechanical? I have tried to balance the IAC's but yesterday I noticed a whiney Squeal coming from top of engine.
Im thinking I have a problem with one of the IAC's , I have the original ones to install and see if the noise goes away.

I did check into balancing throttle bodies and no I have not done that. I am curious if I can use the multiple vacuum gauges I have to do that

well i did the mechanical balancing of throttle bodies, I drove the car with BPW at 124 and it sneezed And coughed , set to 115 and no sneezing but backfiring out of exhaust(new).
I thought I had some data but i figured out I needed to push record button (duh) anyway, I went thru the throttle bodies again late this afternoon and noticed BLM was at 121, int was at 128, then went into closed loop and BLM fell to 108 and idle went to 850 , I should be able to post data a little later this week depending on weather.
Thanks Guy's for your help and patience .
I do have some data but from yesterday @ Idle only.

Closed Loop BLM's above 128 are lean.

Closed Loop BLM's below 128 are rich.

Most TBI computers will "lock" the BLM's @ 128 until closed loop.

The acceptable BLM "averages" range is between 123 ~ 133.

Course tuning typically involves adjusting the Base Pulse Width (BPW) so that most of the BLM's are between 113 ~ 138. Fine tuning typically involves adjusting only the VE table so the BLM averages are between 123 - 133.

dave w

Hey Dave W, thanks for everything,
But this conversion is driving me nuts, no mater where I set BPW the Idle is surging and high (1200), and in C/L the BLM is at 108 I have used the calculator for BPW and from what I have learned the flow rate should be 68/67 between front and rear injectors. which would give a BPW of 121/123. Currently set to 135 ( default). question would be is there any IAC adjustments due to using two IAC's instead of one(typical TBI)

I found the Ebay auction pictures very interesting! https://www.ebay.com/itm/37380293384...BoCJTYQAvD_BwE

Only One TPS and One IAC for both Throttle Bodies.

dave w