Don?t hit rev limiter. - ZR-1 Net Registry Forums

Young1 · 07-21-2022

1990 car. 1991 engine with correct 1991 Haibeck chip. My project idles well and has great drivability. It won?t hit rev limiter in first and second gear. It flattens at 5,000, gets to 6,500 and stops. TPS is .58 at idle. FSM limit is .59. Fuel system pressures are Ok. Secondaries are working I can feel the kick at around 3,500. Vacuum system has been thoroughly checked and tested. Throttle blades visually open 100 percent and air cleaner is new. I have no codes on scanner and no check engine light. It is not making that strong pull of power to rev limiter. What other parameters should I check? Need help. I have a buyer for the car.

tccrab · 07-21-2022

Maybe your accordion air duct is collapsing and restricting your air flow.
If you're sure of fuel and spark, then it's gotta be air.

Crabs

Young1 · 07-21-2022

I have duct supports inside it and I ran it without air cleaner or accordian also. Hmm

efnfast · 07-21-2022

I'm thinking the secondaries are not opening.

tccrab · 07-21-2022

Quote:

Originally Posted by efnfast

I'm thinking the secondaries are not opening.

Or the butterflies are opening, but the secondary injectors aren't squirting fuel.
It's two different operations.

Kinda makes sense, you feel the kick at 3.5k as the butterflies open and extra air is let into the heads, then as RPMs climb the engine goes lean because there's no extra fuel.

Crabs

secondchance · 07-21-2022

I?m with collapsing intake duct.

precast1 · 07-21-2022

Did you get it figured out? Sounds like maybe not enough fuel? Getting closer to PA.

Sent from my SM-G986U using ZR-1 Net Registry mobile app

Young1 · 07-22-2022

Last night I found an obstruction in fuel pressure line. Blew that out and replaced hose assembly. No difference. Tccrab description is exact. It has air to make higher rpm but not fuel. I spliced the power key wires together. Full power light came on but no full power. I removed 91MY Haibeck prom and installed a 90MY SGC prom. It ran hard and fast full power to rev limiter! Once. Next time I tried check engine light came on which means it threw a code. I will check out that code tomorrow. Making progress. I least I know it WILL make full power. Also I need to diagnose the non working cruise control.

XfireZ51 · 07-23-2022

Quote:

Originally Posted by Young1

Last night I found an obstruction in fuel pressure line. Blew that out and replaced hose assembly. No difference. Tccrab description is exact. It has air to make higher rpm but not fuel. I spliced the power key wires together. Full power light came on but no full power. I removed 91MY Haibeck prom and installed a 90MY SGC prom. It ran hard and fast full power to rev limiter! Once. Next time I tried check engine light came on which means it threw a code. I will check out that code tomorrow. Making progress. I least I know it WILL make full power. Also I need to diagnose the non working cruise control.

I?ll bet its a code 61. Lean condition.

fastpace · 07-23-2022

Quote:

Originally Posted by Young1

Last night I found an obstruction in fuel pressure line. Blew that out and replaced hose assembly. No difference. Tccrab description is exact. It has air to make higher rpm but not fuel. I spliced the power key wires together. Full power light came on but no full power. I removed 91MY Haibeck prom and installed a 90MY SGC prom. It ran hard and fast full power to rev limiter! Once. Next time I tried check engine light came on which means it threw a code. I will check out that code tomorrow. Making progress. I least I know it WILL make full power. Also I need to diagnose the non working cruise control.

On the cruise control front there's some good threads on the troubleshooting. Mine was a hole had worn in the vacuum line running to the cruise diaphragm on the drivers side. There's also a vacuum line that runs to a clutch pedal switch too.

07-21-2022	#1
Young1 Join Date: Sep 2016 Location: Ocala, FL Posts: 896	Don?t hit rev limiter. 1990 car. 1991 engine with correct 1991 Haibeck chip. My project idles well and has great drivability. It won?t hit rev limiter in first and second gear. It flattens at 5,000, gets to 6,500 and stops. TPS is .58 at idle. FSM limit is .59. Fuel system pressures are Ok. Secondaries are working I can feel the kick at around 3,500. Vacuum system has been thoroughly checked and tested. Throttle blades visually open 100 percent and air cleaner is new. I have no codes on scanner and no check engine light. It is not making that strong pull of power to rev limiter. What other parameters should I check? Need help. I have a buyer for the car. __________________ Steve Young 1991 ZR-1 Quasar Blue Metallic/Black #729 Second Owner 1991 ZR-1 Dark Red Metallic/Black #2040 SOLD 1990 ZR-1 Dark Red Metallic/Saddle #1670 SOLD Double your happiness.....complain half as much.

07-21-2022	#2
tccrab Join Date: Oct 2004 Location: Folsom CA Posts: 1,654	Re: Don?t hit rev limiter. Maybe your accordion air duct is collapsing and restricting your air flow. If you're sure of fuel and spark, then it's gotta be air. Crabs __________________ TomC '90ZR1 #792 Honorary Pirate [B]If it ain't FUN, you're doing something terribly WRONG. [/B]

07-21-2022	#3
Young1 Join Date: Sep 2016 Location: Ocala, FL Posts: 896	Re: Don?t hit rev limiter. I have duct supports inside it and I ran it without air cleaner or accordian also. Hmm __________________ Steve Young 1991 ZR-1 Quasar Blue Metallic/Black #729 Second Owner 1991 ZR-1 Dark Red Metallic/Black #2040 SOLD 1990 ZR-1 Dark Red Metallic/Saddle #1670 SOLD Double your happiness.....complain half as much.

07-21-2022	#4
efnfast Join Date: Nov 2011 Location: Dunbarton NH Posts: 7,472	Re: Don?t hit rev limiter. I'm thinking the secondaries are not opening.

07-21-2022	#6
secondchance Join Date: Aug 2006 Location: McLean, VA Posts: 3,721	Re: Don?t hit rev limiter. I?m with collapsing intake duct.

07-21-2022	#7
precast1 Join Date: Jan 2018 Location: Apopka, Florida Posts: 143	Re: Don?t hit rev limiter. Did you get it figured out? Sounds like maybe not enough fuel? Getting closer to PA. Sent from my SM-G986U using ZR-1 Net Registry mobile app

07-22-2022	#8
Young1 Join Date: Sep 2016 Location: Ocala, FL Posts: 896	Re: Don?t hit rev limiter. Last night I found an obstruction in fuel pressure line. Blew that out and replaced hose assembly. No difference. Tccrab description is exact. It has air to make higher rpm but not fuel. I spliced the power key wires together. Full power light came on but no full power. I removed 91MY Haibeck prom and installed a 90MY SGC prom. It ran hard and fast full power to rev limiter! Once. Next time I tried check engine light came on which means it threw a code. I will check out that code tomorrow. Making progress. I least I know it WILL make full power. Also I need to diagnose the non working cruise control. __________________ Steve Young 1991 ZR-1 Quasar Blue Metallic/Black #729 Second Owner 1991 ZR-1 Dark Red Metallic/Black #2040 SOLD 1990 ZR-1 Dark Red Metallic/Saddle #1670 SOLD Double your happiness.....complain half as much.