Installed a new motor, but it's not quite right...

So I just swapped an 04 Monte L67 into a 97 Riviera, has 1.9 rockers and 90# springs (new) and 42s, 3.4 pulley, E85 and AEM pump (had before swap) aaand something's off on the top end

Car runs fine, shifts good, but at 3500-4k RPMs it just cuts out. I'll upload a video to show.

Also has a degree or two of KR down low, which is weird because it's not even boosting when it happens.

Vac looks good and fuel pressure looks good, but I'm not sure if it would be a fuel and air issue or if the PCM/TCM needs a tune to work with a newer motor and bigger rockers etc. Any ideas would be appreciated

https://vimeo.com/814645460


Almost sounds like the governor kicking in. In drive of course, but maybe the TCM doesn't realize it?

Spacecowboy067 wrote:

So I just swapped an 04 Monte L67 into a 97 Riviera, has 1.9 rockers and 90# springs (new) and 42s, 3.4 pulley, E85 and AEM pump (had before swap) aaand something's off on the top end

Car runs fine, shifts good, but at 3500-4k RPMs it just cuts out. I'll upload a video to show.

Also has a degree or two of KR down low, which is weird because it's not even boosting when it happens.

Vac looks good and fuel pressure looks good, but I'm not sure if it would be a fuel and air issue or if the PCM/TCM needs a tune to work with a newer motor and bigger rockers etc. Any ideas would be appreciated

can you get the mapping of the Monte's PCM?

albertj wrote:

Spacecowboy067 wrote:

So I just swapped an 04 Monte L67 into a 97 Riviera, has 1.9 rockers and 90# springs (new) and 42s, 3.4 pulley, E85 and AEM pump (had before swap) aaand something's off on the top end

Car runs fine, shifts good, but at 3500-4k RPMs it just cuts out. I'll upload a video to show.

Also has a degree or two of KR down low, which is weird because it's not even boosting when it happens.

Vac looks good and fuel pressure looks good, but I'm not sure if it would be a fuel and air issue or if the PCM/TCM needs a tune to work with a newer motor and bigger rockers etc. Any ideas would be appreciated

can you get the mapping of the Monte's PCM?

Engine didn't come with a PCM, just used the Riv one. Not sure where I would find Monte map info either

I am no expert but you might want to reach out to John @
intense-racing.com
He could certainly make sure you're tune looks right. He might even have a spare PCM to be able to just swap them.

carguy8888 wrote:

I am no expert but you might want to reach out to John @
intense-racing.com
He could certainly make sure you're tune looks right. He might even have a spare PCM to be able to just swap them.

Even just a look-see to compare your mapping would help. Who knows, they might not be different.

Oh by the way - isn't the MAF sensor different on the later L67s than on ours (to '99)? If you used the new TB you might have picked up on that - I figured I'd mention it - if it was me I'd want someone to.

Albertj

albertj wrote:

carguy8888 wrote:

I am no expert but you might want to reach out to John @
intense-racing.com
He could certainly make sure you're tune looks right. He might even have a spare PCM to be able to just swap them.

Even just a look-see to compare your mapping would help.  Who knows, they might not be different.

Oh by the way - isn't the MAF sensor different on the later L67s than on ours (to '99)? If you used the new TB you might have picked up on that - I figured I'd mention it - if it was me I'd want someone to.

Albertj

I actually used the original 97 TB, but the original MAF sensor was acting up so I bought an O'Reilly's one. Not sure if any better, but I wonder if that sensor is 99+ specific...

Well update: installed original TB and MAF, no difference in performance. Got ahold of a fuel pressure tester and... Yup, 20-30 under load. I have a pretty high test AEM fuel pump though, so I don't know if it's failing per se or just not getting enough voltage. Scan tool shows 12.6 volts under load and about 12.7-8ish normally. Is that too low? I might just go back to OEM style fuel pumps, tired of messing with aftermarkets

You need to go through all the tables in the pcm. Do you have HP tuners you can really see more if you can diagnose it with your laptop

Did you swap over all the sensors from the riv engine to the Monte engine. Also are the knock sensors new ?