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1995 Monte Carlo 3.4 DOHC Engine Swap Problem


1Orion
08-07-2014, 02:25 AM
I have a friend who has a 95 Monte Carlo. It had a 3.4 DOHC that was bad. He had a 3.4 DOHC crate engine on the floor so he installed it. Now he finds out the engine he put in hasnt got the sensor down at the crank pulley or up on top for the cam sensor. It only has one in the block. The old engine had the one in the block, One on the crank pulley and one in the head for the cam. The heads have the same cast numbers every thing matches except it was never drilled for the sensor. He believes he can change the pulley and bolt the crank pulley one on, but no way to hook up the cam sensor. Can either of these sensors be by passed beings it has the sensor in the block? There was no donor car as it was a crate engine. It all bolted in fine the only problem is these two sensors. Any ideas or fixs for this problem?

Tech II
08-07-2014, 07:39 AM
I found this info on Wikipedia....One problem you have is, the year...1995 was a transition year....so the car could be OBD I or OBD II, or a transition OBD 1.5.....Your original engine was sequential.....this new engine was multiport, and OBD I....because of this, you will run into computer, engine harness, and sensor problems...a sequential engine needs a cam sensor...there is no getting around that....I think your only hope is to change out the computer, but then that involves changing out the engine wire harness(if you can even find one) too, which is a cluster f#ck, and may not be compatible with your transmission(auto or standard?)....


The LQ1 (also called the Twin Dual Cam or TDC) was a 3.4 L DOHC V6 motor ("X-code") based on the aluminum-headed second generation of GM's 60° engine line, sharing a similar block with its pushrod cousins, the 3.1 L LH0 V6 and the then recently retired 2.8 L LB6 V6. The motor was built only for front wheel drive applications, and was featured exclusively in the first generation of GM's W-body platform.

It was built from 1991 to 1997. From 1991 to 1993, it used tuned multi-port fuel injection, made 200-210 hp (150-160 kW) at 5200 rpm and 215 lb·ft (292 N·m) of torque at 4000 rpm. From 1994 to 1997, it used sequential port fuel injection, making 210 hp (157 kW) at 5200 rpm and 215 lb·ft (292 N·m) of torque at 4000 rpm. In 1996, the heads were redesigned for better flow as well as now making the engine an interference design and adapting the engine for federally mandated OBDII emissions. Output for the 1996-1997 LQ1 is 215 hp (160 kW) and 220 lb·ft (298 N·m). It had four large valves per cylinder. The 3.4 L engine used a cogged belt to drive the four overhead camshafts and a chain to drive the intermediate shaft, which is mounted in the same slot where the camshaft would go in on any of the pushrod engines in the 60-degree family. Adapting a pushrod block for the LQ1's overhead cams was difficult, and the 60° angle made this a very tall engine. The power output for this engine was impressive during its time; however, this engine has never been well liked by auto mechanics, as important maintenance such as spark plug and timing belt changes is very troublesome, especially on later models. Spark plug changes for the three rear cylinders require removing the upper intake manifold when performed as directed by factory service manual, and timing belt changes have a labor rate of 5 hours as opposed to 2-3 for a typical belt-driven engine.

Bore was increased to 92 mm (3.6 in), but the 3.1 L engine's 84 mm (3.3 in) stroke was retained. There are only a few interchangeable parts between this DOHC engine and other members of the 60° family, namely the connecting rods and crankshaft.

The heads and intake manifolds were redesigned for the 1996 model year, incorporating a larger throttle body and plenum area, slightly longer intake runners, cloverleaf combustion chambers, and larger "pill"-shaped exhaust ports. Camshafts and cam timing were also revised for the new, higher rpm powerband.

Optional from 1991 to 1993 was a Getrag 284 5-speed manual transaxle, which was also exclusive to the GM W platform and was available only with the LQ1. The electronically controlled Hydramatic 4T60-E 4-speed automatic transaxle was the alternative, used during the entire production run with the exception of the 1997 Monte Carlo Z34 and 1997 Lumina LTZ, which received the 4T65-E.

Interchange: 1991–1993 models were Multi-port injection, and had a single crank sensor for computer timing. 1994-1995 models used the same long block, but had different cam carriers and timing cover. 1996–1997 models used a modified version of the same short block and had different heads. 91-93 motors cannot be used in later models due to lack of sensors needed for the newer computer systems.

1Orion
08-07-2014, 10:49 AM
I know he wont want to do this but what if he swapped out the head that has the sensor? It has the same cast number and looks the same visually other then no hole for the sensor.

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