Loss of power around 5000 rpms

[Toddmc66]

Recently purchase a 87 T-Type excellent shape. After cleaning up the engine area I took it for a test drive, only getting 10lbs of boost. Engine falls on its face around 4900 to 5000 rpms and you can see the front end lower as the engine stops pulling. Feels as if the timing is backing off or ignition is stumbling. These are the checks and repairs made but problem still exist. No exhaust leaks, no vacuum leaks, set the TPS, check the (Y) or (T) that goes to the boost sensor, turbo and waste gate actuator. Found the (T) has an orfice in it, swapped the two hoses that go to the turbo and actuator, now have 15lbs of boost. Car still continues to fall on its face around 5000 rpms unless I only give it 7/8 throttle and then it pulls hard and continues to pull hard. tried disconnecting the boost sensor (same thing) added a Razor Alcohal Kit (same thing) engine pulls harder with the Razor kit but still has this problem. Sometimes if I keep the pedal to the floor it pulls hard then falls on its face until it shifts into 2nd then pulls hard again untill it reaches the upper rpms. I've also tried adjusting the trans cable, (no change.) Fuel pressure is at 42lbs. These are the upgrade's. 205/210 cam, Red Armstrong double pumper fuel pump, rebuilt factory turbo, Red Armstrong 93 chip, rebuilt factory heads, Razor Alcohol kit using methinol, 55lb injectors, 200R4 rebuilt performace trans with 2800 stall, 3" down pipe 3" exhaust with Dynomax mufflers, Factory rear, E3 spark plugs. Hopefully with all this info someone out there has run into this problem. Sorry to be so long winded.

 

[ZNix]

Red Armstrong 93 chip, E3 spark plugs.

Ok, say goodbye to those spark plugs. I hear they are nothing but trouble. RT43TS gapped at 0.032. Idk but the Armstrong chip but I assume its old. Upgrade to a TT chip that is burned for the modern shitty fuel. Also.. upgraded valve springs?

 

[Toddmc66]

Not sure how old the chip is but the engine runs strong and crisp no misfires at all. Getting a scanner so I can see whats going on. I'll check on the age of the chip. As for the plugs, I've seen alot of dyno test on these and seen good results. Have had them in my Scion and haven't had any problems, infact better mileage and power. Will also check and see if the valve springs were replaced when the heads were done. Thanks.

 

[3.8L V-8 eater]

I was thinking could be weak springs as well.....Also check the gap of the plugs....

 

[SCOOBY DOO]

Valve springs

 

[bison]

The factory turbo is out of breath at 5000 rpm if trying to run boost over 22psi. That cam isn't doing you favors with the stock turbo. E3 plugs are crap for anything more than stock. Good luck trying to gap those

 

[Toddmc66]

Found out from the previous owner the valve springs were shimmed. New springs and turbo on the way, will let you know the results asap thanks for the input.

 

[ZNix]

What turbo and springs did you go with? Just curious.

 

[turbo nasty]

Found out from the previous owner the valve springs were shimmed. New springs and turbo on the way, will let you know the results asap thanks for the input.

Springs are commonly shimmed to get the proper recommended installed height...so that may not be the problem. But if unsure of history or if they are the right ones then ..I would replace them as well.

 

[lrayzer]

I agree, valve springs, but also replace the fuel filter, just because you have 42 lbs at idle does not insure pressure at RPM
The fact that it picks up with alky, could point to fueling, or just cooling of the overheated intake charge from oveboosting the smaller turbo

 

[RIFF RAFF]

The factory turbo is out of breath at 5000 rpm if trying to run boost over 22psi. That cam isn't doing you favors with the stock turbo. E3 plugs are crap for anything more than stock. Good luck trying to gap those

YEEP ..PLUGS !

 

[kidglok]

could try a new set of plugs/wires and a known good coil pack/module

 

[Toddmc66]

Installed new valve springs and that took care of the problem. Engine pull hard all the way through the full rpm range. Also installed t34 turbo, stretch intercooler, valve spring came from Kirban performace.

 

[Toddmc66]

What kind of street / strip tires are most of you using on the street ?

 

[87-WE2]

I run 275/45/17 Kumho Ecsta on the rear (17x10) around the street. My 60' time (at the track) with these is almost exactly the same as with my 235/60/15 BFG Drag Radials on stock 15x7 GN rims. I was pleasantly surprised with the traction of the Kumho's at the track.