I just installed a 05' engine and transmission in a 99' pontiac montana minivan .both engines are similar; 3.4 V6.the point is : the engine dont start.what is wrong? the engine is not compaible? help me please...

check version history, 99 to 05 and then 03 to 05 for coupe.

1999-2005 This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (November 2018) (Learn how and when to remove this template message) Fifth generation Overview Production April 1998-May 10, 2005 Model years Assembly Lansing, Michigan, United States Body and chassis Class Mid-size[34][35] Layout Transverse front-engine, front-wheel drive Platform N-body Related

• Oldsmobile Alero
• Oldsmobile Cutlass
• Chevrolet Malibu

Powertrain Engine

• 2.2 L L61 Ecotec I4
• 2.4 L LD9 Twin Cam I4
• 3.4 L LA1 V6

Transmission 5-speed Getrag F23 manual
4-speed 4T40-E automatic
4-speed 4T45-E automatic Dimensions Wheelbase 107.0 in (2,718 mm)[36] Length 186.3 in (4,732 mm) Width 70.6 in (1,793 mm) (1999-2000)
70.4 in (1,788 mm) (2001-05) Height 54.5 in (1,384 mm) (1999-2000)
55.1 in (1,400 mm) (2001-05) Curb weight Coupe: 3,066 lb (1,391 kg)
Sedan: 3,116 lb (1,413 kg)[37] Available in late spring 1998, the basic design of the fifth-generation Grand Am was shared with the Oldsmobile Alero (also new for 1999) and Chevrolet Malibu (introduced in 1996). The length was shortened slightly, but the wheelbase grew by more than three inches (76 mm). The suspension was now fully independent, with a revised MacPherson-Strut design upfront. The rear suspension is a more refined Multi-link design. The new Grand Am was offered in five trim levels: SE, SE1, SE2, GT, and GT1. The 2.4 L Twin Cam engine was carried over, with 150 hp (112 kW; 152 PS) and 155 lb?ft (210 N?m) of torque. GM's 3400 V6, previously exclusive to their minivans, became available as an option on the SE and SE1 and was standard on all other trim levels. For 1999, all the Grand Ams featured a 4-speed automatic transmission. The GT and GT1 also included 4-wheel disc brakes,[38] and all Grand Ams until 2003 included standard ABS and Traction Control (made optional on SE from 2003). The GTs also had a Ram Air induction system, providing an extra five horsepower and 5 lb/ft of torque over the 3.4 L V6 when installed in any of the SE-level trims.
The 2000 models added a Getrag 5-speed manual transmission as standard equipment with the four-cylinder. On GT models, the badge on the front fenders now read "RamAir V6", instead of "V6H.O." on 1999 GT's. ASC Creative Services designed the Grand Am SC/T for the SEMA show circuit, which was the concept design for the Ram Air hood and body package. The SC/T later became an appearance package, beginning in 2003. A road test by Car and Driver showed a 0-60 mph time of 7.7 seconds in a GT sedan with an automatic.[36]
For 2001, the SE2 trim level was dropped, a new family of Delco stereos and new wheel designs was introduced. The radio size in 2001 also changed from a 1.5 DIN size to a full 2 DIN size. Halfway through 2002, the Twin Cam 2.4 L engine was replaced by a new 2.2 L Ecotec four-cylinder, which had improvements over the engine it replaced, but produced less output; 140 hp (104 kW; 142 PS) and 150 lb?ft (203 N?m) of torque. Changes for 2002 also included a stationary cup holder in the center console as opposed to a removable one.
The body cladding on SE models was removed in 2003, a change which affected other models throughout Pontiac. Also in 2003, anti-lock brakes and traction control were made optional on the SE. In 2004, an MP3 player was added to the uplevel CD player. In 2005, Pontiac began phasing out the Grand Am lineup for the new G6 replacement. SE sedans were retained for fleet sale and GT coupes were the last Grand Am model available for public sale.

2003-2005 Pontiac Grand Am GT coupe The final Grand Am rolled off the line at Lansing, Michigan's, Lansing Car Assembly plant on May 10, 2005, shortly before the Lake Orion, Michigan plant began assembling G6 coupes. This was also the last car to be made at Lansing's old Fisher Body plant.
Available engines:

• 1999-2002: 2.4 L DOHC Twin Cam L4 (LD9 model) engine: 150 hp (110 kW), 155 lb?ft (210 N?m) of torque
• 2002-2005: 2.2 L DOHC Ecotec L4 engine: 140 hp (100 kW), 150 lb?ft (200 N?m) of torque
• 1999-2005: 3.4 L 3400 OHV V6: 170 hp,(175 for GT) 200 lb?ft (270 N?m) of torque (205 for GT)[39]

Available transmissions:

• 1999-2005: 4-speed automatic with overdrive (4T40-E for four-cylinder engines, 4T45-E for V6 engines)
• 2000-2005: Getrag 5-speed manual with overdrive (four-cylinder engines only)

Yes 97 98 99 are all the same.

I’m happy to help further over the phone at https://www.6ya.com/expert/fred_9ea6f00d14da8ce5

That sensor is in the exhaust system near or on the catalytic converter under the car.

As you see I provided you the models you can apply the transmission :The 4T65E-HD (code MN7) is a heavy duty version of the 4T65-E used with more powerful engines such as the LS4 V8 and L67/L32 supercharged V6. Applications: 2.93:1 MN7 Pontiac Bonneville SSEi L67 Chevrolet Impala L67 Chevrolet Monte Carlo L67 Pontiac Grand Prix GTP/GXP Buick Regal GS Buick Riviera L67 (97-99) So ,yes you can!

You can call any GM dealer with your Serial/VIN number of the car and they can tell you what engine you have. There is also a emissions sticker under the hood that gives the engine size. You have 2 choices the 3.5 Liter V6 or the 3.9 Liter V6.

maybe just temporary--but usually means 02 sensor conditions or vacuum leak--get car scanned with a tech ll

The three front ones are simple and the three back ones are challenging. There are two ways to replacing the rear spark plugs on the Montana.
1. If your arms are long enough and you have longs extensions with a spark plug socket with a swivel build in to it, you can get to the plugs from under the Montana.
2. You can get to the rear plugs buy disconnecting the two dog bone engine mounts in front of the engine and tilting the engine forward. You can do this by placing the parking brakes on and disconnecting the dog bone, once that is done. Place your foot on the brakes and take the parking brakes off and push the Montana forward till the engine tilts forward enough to give you the room you need to get your arms over the top of the engine with the extensions and spark plug socket. Make sure you place the parking brakes back on and put a block at the rear of the engine to ensure the Montana will not move back and cause you to loose your arm or head.
Note that you need to keep the transmission in park when tilting the engine and that your going to have to replace the spark plug wires and do everything by touch to replace the rear spark plugs.
Thank you for using Fixya and use platinum spark plugs to give you 100,000 miles of service. Good luck and be safe.

Go to Autozone and they will check your cars trouble codes for free and tell you what part you will need to replace. They are usually right 99% of the time.The crankshaft position sensor located behind the harmonic balancer maybe be bad. There is another crankshaft position sensor located on the engine block above and to the right of the oil filter. Or it could be the power train control module located to the right of the air cleaner box. This information is for the V6 3.4 engine. Buy the repair manual for your Montana and go to the engine performance section. The manual costs about $26.00

aye lower intake gasket 50-60,000 mi
but i like the 3400 its a strong engine.

Have you checked your brakes