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Hey guy finally got my 98 formula back on the road after some work i installed cam, long tubes and swapped heads, also installed ractronix 255 with hot wire kit, FAST 36lb injectors, and nitrous outlet plate kit, car is running fine except at WOT after about 6k RPM it will begin to stutter and loose power all the hands in the cluster will start bouncing and lights flickering around then it will pick back up and run fine but I got to do a TPS relearn to get it to idle correct after this happens. New Br7ef plugs and MSD wires as well car had o2 sensors deleted was tuned by Frost. Fuel PSI is holding around 60lbs even when the cutout is happening according to my fuel gauge in the car. Even on a WOT pull if i let off about 5800 it will start doing it as soon as i let off the the throttle and all the gauge cluster will go crazy Any ideas?
***also to add did change TPS sensor with another one from a running ls1 still nothing only codes is knock sensor codes**
Sounds like it has someting to do with electronics. What did you do for valve springs?
Tick performance 660s, im thinking it could be alternator, belt, or tensioner pulley, when it does it it acts just like when a alternator starts to goes bad.
Interesting...I've been dealing with voltage drop on my 01 also and I put another alternator in a few weeks back but still having voltage drops and i just replaced the tensioner today.
Interesting...I've been dealing with voltage drop on my 01 also and I put another alternator in a few weeks back but still having voltage drops and i just replaced the tensioner today.
Changed belts to a new continental still doing it I did notice on a WOT pull it's not shifting correctly pulled 7k rpm and still no shift I let off and it done it again I'm beginning to wonder if the shift points/ rev limiter is s set tso high in the tune for the setup causing it to over spin the stock alternator
...email Frost with more details waiting to hear back
Thinking I may have found the problem/problems since I have so many spare parts I figured I would change the coils, wires, and alternator (another 105amp) well when replacing this stuff I discovered 2 issues that could be affecting it I will post pics, I'm going to change/fix them and go from there.
Anddd still doing it was doing good nice clean pull through the gears and then started again, could the 105 amp alternator be the problem maybe the load from the hot wire kit gauge pods etc be to much at upper rpm or over spinning or a bad MAF ? I have changed belts, tensioner (stock), coil packs, plug wires, and alternators (105)..also no burn marks I could see from anything.
Pretty sure the max alt rpm is about 18K for the stock alt.. Your can search this forum for discussions about this issue. And also for the formula to determine alt rpm.
Powermaster has a white paper on this subject as well. Search their website. If you loose voltage at high rpm the pump will not pump pressure and volume maximum either;
Don't know if you can test at night with headlights on - if they dim at high rpm might tell you what the issue is. At the track at night you see some lights dim in the water box at very high rpms.
Are you running an underdrive pulley on the crank? My 98 Z alt has only 1 red wire. You can buy the one wire pigtail. Pretty sure when you buy a replacement that you have to specify one wire.
Last edited by dlandsvZ28; 06-25-2022 at 07:03 PM.
Reason: edit content
Pretty sure the max alt rpm is about 18K for the stock alt.. Your can search this forum for discussions about this issue. And also for the formula to determine alt rpm.
Powermaster has a white paper on this subject as well. Search their website. If you loose voltage at high rpm the pump will not pump pressure and volume maximum either;
Don't know if you can test at night with headlights on - if they dim at high rpm might tell you what the issue is. At the track at night you see some lights dim in the water box at very high rpms.
Are you running an underdrive pulley on the crank? My 98 Z alt has only 1 red wire. You can buy the one wire pigtail. Pretty sure when you buy a replacement that you have to specify one wire.
I haven't tried at night yet to see I will give that a try, and no UD just a trickflow harmonic damper.
So I may have found the possible problem if not related to.this it's still a problem lol, so i was going to replace the cam position sensor well before doing I was checking all the wiring when I got back to the PCM I barley touched it and the car died. I started it back up and wiggled the PCM and it died again. So I took off the connectors wiped them with a clean rag plugged it back up tq down and started the car as soon as I touched the pcm car died again. Im wondering if this could be what's causing my problem? When I got the car the previous owner had made a hack job of the connectors etc for fuel injectors, map sensor all wiring etc. But I'm still thinking it's alternator related just have that feeling.
Did you replace the one wire plug to the alternator. Pretty it controls voltage to the PCM and also regulates voltage to the battery.
I did not get a new connector just ran a new wire from where the other was broken odly enough a long piece of wire not sure how the previous owner had it ran. Think it could be the connector?
Not a pro but I think RPM is derived from CAM sensor not Crank sensor. But I think you losing speedo means neither of those is the main problem.
Crank sensor outage is fatal (unlike cam sensor) and would indeed stop engine I'm pretty sure, but would not make your gas gauge peg as shown.
Also, I believe if the alternator just "stopped charging" you'd have quite a bit of time left in the battery to continue through the pull, and the volt gauge going down to just battery voltage seems like the car just sorta "powered off".
This looks like entire PCM losing power/ground to me.
The fact your mileage also blinked might be a clue, does the gauge cluster and PCM share a ground or fuse? That's where I'd start. Again I'm not a pro, just throwing in my 2cents
"So I may have found the possible problem if not related to.this it's still a problem lol, so i was going to replace the cam position sensor well before doing I was checking all the wiring when I got back to the PCM I barley touched it and the car died. I started it back up and wiggled the PCM and it died again. So I took off the connectors wiped them with a clean rag plugged it back up tq down and started the car as soon as I touched the pcm car died again. Im wondering if this could be what's causing my problem"?
Sounds to me as tho you've answered your own question.
Replace/repair the hack job you inherited and see what comes up next.
Frost's tune has nothing to do with this.
EDITED for error. Not a pro but I think RPM is derived from CAM sensor not Crank sensor. But I think you losing speedo means neither of those is the main problem.
RPM comes from crank sensor. BUT cam sensor code will kill the tach, I don't know if this is deliberate or accidental in the OS coding. Set cam sensor to not report error, and your tach will work even with the cam sensor unplugged.
Crank sensor outage is fatal (unlike cam sensor) and would indeed stop engine I'm pretty sure, but would not make your gas gauge peg as shown.
correct
This looks like entire PCM losing power/ground to me.
This whole issue reminds of the issue when f body owners leave the battery unsecured and the battery rocks back and the positive terminal hits the AC dryer. Car power resets, but you don't notice it bucking, because the car is in gear and as soon as power resets the engine turns back over from the car moving and you keep going.
Agreed... Looks like the car is losing power either from a bad 12v power supply or a ground wire connection. Check all connections at the fuse box, pcm, check the large grounds at the heads/block etc.
06-20-2022, 06:42 PM
Cutting out over 6k rpm **NOW WITH VIDEO** 
